U.S.S. THREADFIN (SS-410) — war patrol report SS-410_THREADFIN.pdf

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START OF REEL
JOB NO. [HANDWRITTEN: B-108-AR-184-75]
[HANDWRITTEN: R-1]

1.0
1.1
1.25
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OPERATOR [HANDWRITTEN: Havens]
DATE [HANDWRITTEN: 6-10-75]

THIS MICROFILM IS
THE PROPERTY OF
THE UNITED STATES
GOVERNMENT

[SEAL: DEPARTMENT OF DEFENSE, UNITED STATES OF AMERICA]

MICROFILMED BY
NPPSO-NAVAL DISTRICT WASHINGTON
MICROFILM SECTION

REEL TARGET, START & END
NAVEXOS 3968

— page 2 —
S3410/A4-3
Serial (010)
[STAMP: DECLASSIFIED]
[STAMP: DECLASSIFIED ART. 0445, OPNAVINST 5510.10]
[HANDWRITTEN: BY G.C.R. DATE 6/20/72]

U.S.S. THREADFIN (SS410)
Care Fleet Post Office,
San Francisco, California,
16 February 1945.

From: The Commanding Officer, U.S.S. THREADFIN.
To: The Commander in Chief, U.S. Fleet.
Via: (1) The Commander Submarine Division THREE TWENTY ONE.
     (2) The Commander Submarine Squadron THIRTY TWO.
     (3) The Commander Submarine Force, U.S. Pacific Fleet.
     (4) The Commander in Chief, US. Pacific Fleet.

Subject: U.S.S. THREADFIN (SS410) - Report of War Patrol
         Number ONE.

Enclosure: (A) Subject Report.
         (B) Track Chart. (ComSubsPac Only).

1. Enclosure (A) covering the First War Patrol of this
vessel conducted in the areas Southeast of the JAPANESE EMPIRE
North of Lat. 30° North and West of Long. 136° East during the
period 25 December, 1944 to 16 February, 1945, is forwarded here-
with.

[SIGNATURE: J.J. FOOTE.]

[HANDWRITTEN: FILMED]
[HANDWRITTEN: 110809]

— page 23 —
CONFIDENTIAL                                                              U.S.S. THREADFIN (SS:410)

No. | (F) | SHIP CONTS:           | Lat. (N)      | Type(s)        | Initial Est. | C&S       | How       | Remarks
    |     | Date      Time (I)    | Long. (E)     |                | Tonnage      |           | Contacted |
----|-----|||||||
1.  |     | 1251      33-19.5     | Hospital      | 13,100         | 255°      | P         | Not identified as AH
    |     | 1/27      135-35.7    | Ship          | @15 kts.       | 12 kts.   |           | until 2300 (I).
2.  |     | 1619      33-12.4     | 4 Catcher Type | 6,000          | 085°      | P         | Patrolling between IGHE
    |     | 1/28      134-10.0    | Patrol Boats  |                | 6 kts.    |           | Saki and SHIONO MISAKI.
3.  |     | 1058      33-27.2     | 1 Catcher Type | 5,000          | 270°      | P         | Patrolling Coast.
    |     | 1/29      135-32.0    | Patrol Boat   |                | 8 kts.    |           |
4-a.|     | 0620      33-29.0     | PC Patrol     | 5,000          | 110°      | S         | Escorted by 2 PC's
    |     | 1/30      135-35.3    | Boat.         |                | 10 kts.   |           | (on track #1)
4-abo.|   | 0653      33-29.0     | Small A/S     | 9,000          | 110°      | P         | Joined in search after
    |     | 1/30      135-35.7    | & 2 PC's      |                | 10 kts.   |           | attack #1.
5.  |     | 0900      33-25.0     | 5 A/S vessels.| 6,000          | Various   | P         | Searching.
    |     | 1/30      135-30.0    |               |                |           |           |
5-a.|     | 1013      33-20.5     | PC            | 6,000          | Various   | P         | Searching.
    |     | 1/30      135-30.5    |               |                |           |           |
5-b.|     | 1451      33-16       | PC            | [UNCLEAR: Zigzag] | 305°      | P         | RO-60 Class (EU).
    |     | 1/30      135-26      |               |                | 13 kts.   |           |
6.  |     | 0803      32-01.5     | Submarine     | 8,000          | 310°      | S         | AM-13 Class (EU).
    |     | 2/1       133-38.5    |               |                | 10 kts.   |           |
7.  |     | 0858      33-29.5     | A/S vessel    | 10,000         | 310°      | S         | AM-13 Class (EU).
    |     | 2/6       135-35.0    |               |                | 10 kts.   |           |

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— page 24 —
U.S.S. THREADFIN (SS410)

CONFIDENTIAL
(G) AIRCRAFT CONTACTS:

| | | 1 | 2 | 3 | 4 | 5 | 6 |
|---|---|---|---|---|---|---|---|
| | Contact Number | | | | | | |
| | Date | 1/11 | 1/12 | 1/13 | 1/13 | 1/13 | 1/13 |
| S | Time | 1658(I) | 1825(I) | 0920(I) | 0940(I) | 1000(I) | 1105(I) |
| U | Position: Lat.(N) | 31-33 | 31-27 | 31-29 | 31-29 | 31-29 | 31-31 |
| B | Long.(E) | 131-43 | 131-47 | 131-26 | 131-26 | 131-26 | 131-27 |
| M | Speed (knots) | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 |
| A | Trim | Subm. | Subm. | Subm. | Subm. | Subm. | Subm. |
| R | Min. since last | Subm. | Subm. | Subm. | Subm. | Subm. | Subm. |
| I | SD Radar Search | | | | | | |
| N | Number | 1 | 1 | 20 | 1 | 6 | 3 |
| E | Type | Unk. | Unk. | Kates | Cherry | Unk. | Unk. |
| A | Probable mission | - | - | - | * | * | * |
| I | How Contacted | P | P | P | P | P | P |
| R | Initial Range | 5-7 Mi. | 5-7 Mi. | 4 Mi. | 12 Mi. | 10 Mi. | 10 Mi. |
| C | Elevation angle | 5° | 5° | 4° | 3° | 1° | 2° |
| R | Range & Relative | | | | | | |
| A | Bearing of Plane | ND | ND | ND | ND | ND | ND |
| F | When it Detected | | | | | | |
| T | S/M | | | | | | |
| C | Sea (State Beau. | 2 | 2 | 2 | 2 | 2 | 2 |
| O | Direction(Rel) | 310° | 270° | 000° | 000° | 000° | 000° |
| N | Visibility(Miles) | Unltd. | Unltd. | Unltd. | Unltd. | Unltd. | Unltd. |
| D | Height(Ft) | 3,000 | 3,000 | 2,000 | 2,000 | 2,000 | 2,000 |
| I | Clouds (%Overcast | 50 | 50 | 50 | 70 | 80 | 85 |
| T | Bearing (Rel) | -- | -- | -- | -- | -- | -- |
| I | M angle | -- | -- | -- | -- | -- | -- |
| O | % Illuminated | -- | -- | -- | -- | -- | -- |
| N | | | | | | | |

Type of S/M Camouflage on this patrol - Haze Grey.

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— page 25 —
CONFIDENTIAL
U.S.S. THREADFIN (SS410)

(G) AIRCRAFT CONTACTS:

| | 7 | 8 | 9 | 10 | 11 | 12 |
| :| :------ | :------ | :------ | :------ | :------ | :------ |
| Contact Number | | | | | | |
| Date | 1/13 | 1/13 | 1/13 | 1/14 | 1/14 | 1/15 |
| S U B M A R I N E | Time | 1220(I) | 1440(I) | 1500(I) | 1120(I) | 1125(I) | 0852(I) |
| | Position: Lat. (N) | 31-32 | 31-35 | 31-36 | 32-28 | 32-28 | 32-40 |
| | Long. (E) | 131-27 | 131-27 | 131-28 | 132-18 | 132-17 | 132-01 |
| | Speed (knots) | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 |
| | Trim | Subm. | Subm. | Subm. | Subm. | Subm. | Subm. |
| | Min. since last SD Radar Search | Subm. | Subm. | Subm. | Subm. | Subm. | Subm. |
| A I R C R A F T | Number | 1 | 3 | 3 | 1 | 1 | 1 |
| | Type | Unk. | Nell | Unk. | Betty | Cherry | Jake |
| | Probable mission | * | * | * | - | Patrol | Patrol |
| | How Contacted | P | P | P | P | P | P |
| | Initial Range | 12 Mi. | 12 Mi. | 12 Mi. | 10 Mi. | 10 Mi. | 3 Mi. |
| | Elevation Angle | 2° | 1° | 2° | 2° | 2° | 5° |
| | Range & Relative Bearing of Plane When it Detected S/M | ND | ND | ND | ND | ND | ND |
| C O N D I T I O N S | State Beau. | 1 | 1 | 1 | 3 | 3 | 4 |
| | Sea (Direction (Rel) | 020° | 020° | 200° | 040° | 050° | 015° |
| | Visibility (Mi.) | Unltd. | Unltd. | Unltd. | Unltd. | Unltd. | Unltd. |
| | Height (Ft.) | 2,300 | 2,500 | 2,500 | 2,000 | 2,000 | 3,500 |
| | Clouds (%Overcast | 60 | 50 | 60 | 20 | 20 | 40 |
| M O O N S | Bearing (Rel) | -- | -- | -- | -- | -- | -- |
| | Angle | -- | -- | -- | -- | -- | -- |
| | %Illuminated | -- | -- | -- | -- | -- | -- |

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— page 26 —
U.S.S. THREADFIN (SS410)
CONFIDENTIAL
(G) AIRCRAFT CONTACTS:

| | Contact Number | 13 | 14 | 15 | 16 | 17 | 18 |
|---|---|---|---|---|---|---|---|
| | Date | 1/15 | 1/15 | 1/15 | 1/15 | 1/15 | 1/16 |
| S | Time | 0935(I) | 1006(I) | 1025(I) | 1345(I) | 1415(I) | 1211(I) |
| U | Position: Lat. (N) | 32-37 | 32-37 | 32-36 | 32-37 | 32-37 | 32-38 |
| B | Long. (E) | 132-02 | 132-03 | 132-04 | 132-07 | 132-07 | 132-27 |
| M | Speed (knots) | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 | 3.0 |
| A | Trim | Subm. | Subm. | Subm. | Subm. | Subm. | Subm. |
| R | Min. Since Last | | | | | | |
| I | SD Radar Search | Subm. | Subm. | Subm. | Subm. | Subm. | Subm. |
| N | Number | 3 | 2 | 2 | 6 | 5 | 1 |
| E | Type | Unk. | Cherry | Unk. | Unk. | Unk. | Lily |
| A | Probable mission | -- | Patrol | Patrol | -- | -- | Patrol |
| I | How Contacted | P | P | P | P | P | P |
| R | Initial Range | 8 Mi. | 7 Mi. | 7 Mi. | 15 Mi. | 14 Mi. | 10 Mi. |
| C | Elevation Angle | 3° | 4° | 2° | 2° | 2° | 4° |
| R | Range & Relative | | | | | | |
| A | Bearing of Plane | | | | | | |
| F | When it Detected | ND | ND | ND | ND | ND | ND |
| T | S/M | | | | | | |
| | State (Beau.) | 4 | 4 | 3 | 4 | 4 | 4 |
| C | Sea Direction (Rel.) | 240° | 240° | 240° | 240° | 250° | 240° |
| O | Visibility (Mi.) | Unltd. | Unltd. | Unltd. | Unltd. | Unltd. | Unltd. |
| N | Clouds (Height (Ft.) | 4,000 | 4,000 | 4,000 | 4,000 | 3,500 | 2,500 |
| D | %Overcast | 30 | 30 | 30 | 50 | 50 | 85 |
| I | M Bearing (Rel.) | -- | -- | -- | -- | -- | -- |
| T | O Angle | -- | -- | -- | -- | -- | -- |
| I | N % Illuminated | -- | -- | -- | -- | -- | -- |
| O | | | | | | | |
| N | | | | | | | |
| S | | | | | | | |

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— page 27 —
CONFIDENTIALL
U.S.S. THREADFIN (SS410)

(G) AIRCRAFT CONTACTS:
| | 19 | 20 | 21 | 22 | 23 | 24 |
|---|---|---|---|---|---|---|
| Contact Number | | | | | | |
| Date | 1/16 | 1/16 | 1/17 | 1/17 | 1/18 | 1/18 |
| S | Time | 1223(I) | 1358(I) | 1205(I) | 1430(I) | 1134(I) | 1325(I) |
| U | Position: Lat. (N) | 32-39 | 32-39 | 32-42 | 32-39 | 32-44 | 32-43 |
| B | Long. (E) | 132-29 | 132-29 | 133-09 | 133-10 | 132-17 | 132-22 |
| M | Speed (knots) | 3.0 | 3.0 | 1.5 | 1.5 | 1.5 | 1.5 |
| A | Trim | Subm. | Subm. | Subm. | Subm. | Subm. | Subm. |
| R | Min. Since Last | | | | | | |
| I | SD Radar Search | Subm. | Subm. | Subm. | Subm. | Subm. | Subm. |
| N | Number | 1 | 1 | 5 | 1 | 1 | 3 |
| E | Type | Jake | Jake | Betty | Betty | Emily | Hop |
| A | Probable Mission | Patrol | Patrol | -- | -- | Patrol | -- |
| I | How Contacted | P | P | P | P | P | P |
| R | Initial Range | 4 Mi. | 3 Mi. | 10 Mi. | 8 Mi. | 8 Mi. | 3 Mi. |
| C | Elevation Angle | 3° | 3° | 2° | 2° | 2° | 3° |
| R | Range & Relative | | | | | | |
| A | Bearing of Plane | ND | ND | ND | ND | ND | ND |
| F | When it Detected | | | | | | |
| T | S/M | | | | | | |
| C | State(Beau.) | 4 | 4 | 3 | 4 | 4 | 4 |
| O | Sea (Direction(Rel.)) | | | 270° | 040° | 220° | 220° |
| N | Visibility (Mi) | Unltd. | Unltd. | Unltd. | Unltd. | 12 | Unltd. |
| D | Height(Ft.) | 2,500 | 2,500 | 3,000 | 3,000 | 3,500 | 4,000 |
| I | Clouds(% Overcast) | 85 | 80 | 50 | 50 | 6 | 6 |
| T | Bearing (Rel.) | -- | -- | -- | -- | -- | -- |
| I | Angle | -- | -- | -- | -- | -- | -- |
| O | % Illuminated | -- | -- | -- | -- | -- | -- |
| N | | | | | | |
| S | | | | | | |

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— page 28 —
U.S.S. THREADFIN (SS410)

CONFIDENTIAL

(G) AIRCRAFT CONTACTS:

Contact Number | 25 | 26 | 27 | 28 | 29 | 30
Date | 1/18 | 1/18 | 1/18 | 1/19 | 1/19 | 1/20
Time | 1345(I) | 1425(I) | 1433(I) | 1535(I) | 2258(I) | 1300(I)
Position: Lat. (N) | 32-43 | 32-42 | 32-42 | 31-54 | 32-10 | 31-58
Long. (E) | 132-23 | 132-22 | 132-22 | 133-19 | 133-54 | 133-08
Speed (knots) | 1.5 | 1.5 | 1.5 | 1.5 | 8 | 1.5
Trim | Subm. | Subm. | Subm. | Subm. | Surf. | Subm.
Min. Since Last SD Radar Search | Subm. | Subm. | Subm. | Subm. | N.U. | Subm.
Number | 1 | 1 | 3 | 1 | 2-3 | 1
Type | Unk. | Unk. | Unk. | Betty | Unk. | Jake
Probable Mission | -- | -- | -- | Patrol | -- | Patrol
How Contacted | P | P | P | P | S | P
Initial Range | 12 Mi. | 6 Mi. | 14 Mi. | 12 Mi | 4-5 Mi. | 10 Mi.
Elevation Angle | 2° | 2° | 1° | 2° | 5° | 2°
Range & Relative Bearing of Plane When it Detected S/M | ND | ND | ND | ND | ND | ND
State (Beau.) | 4 | 4 | 4 | 2 | 3 | 3
Direction (Rel.) | 220° | 090° | 090° | 210° | 320° | 045°
Visibility (Mi.) | 12 | 15 | 15 | Unltd. | 12 | 12
Height (Ft.) | 4,000 | 4,000 | 4,000 | 4,000 | 4,000 | 3,500
Clouds (% Overcast) | 6 | 7 | 7 | 70 | 70 | 65
Bearing (Rel.) | -- | -- | -- | -- | -- | --
Angle | -- | -- | -- | -- | -- | --
% Illuminated | -- | -- | -- | Beneath Clouds | -- | --

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— page 29 —
J.S.S. THREADFIN (SS410).
CONFIDENTIAL
(G) AIRCRAFT CONTACTS:

| | | 31 | 32 | 33 | 34 | 35 | 36 |
|---|---|---|---|---|---|---|---|
| | Contact Number | 1/20 | 1/21 | 1/21 | 1/21 | 1/21 | 1/21 |
| | Date | | | | | | |
| S | Time | 1825(I) | 0923(I) | 0950(I) | 1129(I) | 1300(I) | 1826(I) |
| U | Position: Lat. (N) | 32-02 | 32-16 | 32-16 | 32-16 | 32-16 | 32-16 |
| B | Long. (E) | 133-00 | 132-31 | 132-30 | 132-31 | 132-31 | 132-31 |
| M | Speed (knots) | 8 | 1.5 | 1.5 | 1.5 | 1.5 | 14 |
| A | Trim | Surf. | Subm. | Subm. | Subm. | Subm. | Surf. |
| R | Min Since Last | N.U. | Subm. | Subm. | Subm. | Subm. | N.U. |
| I | SD Radar Search | | | | | | |
| N | Number | 3 | 1 | 1 | 1 | 1 | 1 |
| E | | | | | | | |
| A | Probable Mission | Unk. | Patrol | Unk. | Patrol | Unk. | Unk. |
| I | Type | Unk. | Jake | D-2 | Jake | Betty | Unk. |
| R | How Contacted | S | P | P | P | P | S |
| C | Initial Range | 6 Mi. | 5 Mi. | 4 Mi. | 3 Mi. | 5 Mi. | 5 Mi. |
| R | Elevation Angle | 4° | 3° | 1° | 4° | 3° | 4° |
| A | Range & Relative | | | | | | |
| F | Bearing of Plane | ND | ND | ND | ND | ND | ND |
| T | When it Detected | | | | | | |
| | S/M | | | | | | |
| C | State (Beau.) | 3 | 3 | 3 | 4 | 5 | 5 |
| O | Sea | Direction (Rel) | 045° | 090° | 090° | 090° | 090° | 260° |
| N | Visibility (Mi.) | 10 | 8 | 10 | 15 | 15 | 15 |
| D | Height (Ft.) | 3,500 | 3,000 | 3,000 | 3,000 | 3,000 | 3,000 |
| I | Clouds | % Overcast | 70 | 90 | 100 | 80 | 70 | 70 |
| T | Bearing (Rel.) | Beneath | -- | -- | -- | -- | Beneath |
| I | | Clouds | | | | | | Clouds |
| O | Angle | do | -- | -- | -- | -- | do |
| N | % Illuminated | do | -- | -- | -- | -- | do |
| S | | | | | | | |

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— page 30 —
CONFIDENTIAL
U.S.S. THREADFIN (SS410)

(G) AIRCRAFT CONTACTS:
                                | 37       | 38       | 39       | 40       | 41       | 42
Contact Number                  |          |          |          |          |          |
Date                            | 1/23     | 1/23     | 1/24     | 1/24     | 1/24     | 1/24
S   Time                        | 0945(I)  | 1125(I)  | 1108(I)  | 1850(I)  | 1900(I)  | 1910(I)
U   Position: Lat. (N)          | 32-14    | 32-17    | 32-42    | 32-31    | 32-31    | 32-31
B   Position: Long. (E)         | 132-48   | 131-50   | 132-13   | 132-22   | 132-22   | 132-24
M   Speed (knots)               | 1.5      | 1.5      | 1.5      | 9        | 9        | 9
A   Trim                        | Subm.    | Subm.    | Subm.    | Surf.    | Surf.    | Surf.
R   Min. Since Last             | Subm.    | Subm.    | Subm.    | 15"      | 25"      | 35"
I   SD Radar Search             |          |          |          |          |          |
N   Number                      | 70       | 1        | 1        | 1        | 1        | 1
E
    Type                        | Val      | Emily    | Cherry   | Unk.     | Unk.     | Unk.
A   Probable Mission            | --       | Patrol   | Patrol   | --       | --       | --
I   Initial Range               | 4-15     | 6 Mi     | 3 Mi.    | 10.I.    | 5 Mi.    | 3.5 Mi.
R   How Contacted               | P        | P        | P        | S        | P        | P
C   Elevation Angle             | 2°       | 4°       | 2°       | 3°       | 3°       | 4°
R   Range & Relative            |          |          |          |          |          |
A   Bearing of Plane            | ND       | ND       | ND       | ND       | ND       | ND
F   When it Detected            |          |          |          |          |          |
T   S/M                         |          |          |          |          |          |
    State (Beau.)               | 4        | 3        | 5        | 4        | 4        | 4
C   Sea (Direction (Rel.)       | 320°     | 320°     | 270°     | 230°     | 230°     | 230°
O   Visibility (Mi.)            | Unltd.   | Unltd.   | 15       | Unltd.   | Unltd.   | Unltd.
N   Height (Ft.)                | 4,000    | 3,500    | 4,000    | 4,000    | 4,000    | 4,000
D   Clouds (% Overcast          | 50       | 50       | 90       | 90       | 90       | 90
I   Bearing (Rel.)              | --       | --       | --       | Beneath the Clouds. | do | do
T   O. Angle                    | --       | --       | --       | do       | do       | do
I   N % Illuminated             | --       | --       | --       | do       | do       | do
O
N
S

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— page 31 —
CONFIDENTIAL
U.S.S. THREADFIN (SS410)

(G) AIRCRAFT CONTACTS:

Contact Number | 43 | 44 | 45 | 46 | 47 | 48
Date | 1/24 | 1/25 | 1/25 | 1/25 | 1/25 | 1/25
Time | 1920(I) | 1117(I) | 1211(I) | 1215(I) | 1258(I) | 1334(I)
Position: Lat. (N) | 32-15 | 33-11 | 33-12 | 33-13 | 33-13 | 33-13
Long. (E) | 132-25 | 134-15 | 134-15 | 134-15 | 132-15 | 132-15
Speed (knots) | 9 | 1.5 | 1.5 | 1.5 | 1.5 | 1.5
Trim | Surf. | Subm. | Subm. | Subm. | Subm. | Subm.
Min. Since Last | N.U. | Subm. | Subm. | Subm. | Subm. | Subm.
SD Radar Search
Number | 3 | 1 | 1 | 1 | 1 | 8
Type | Unk. | Unk. | Betty | Fighter | Unk. | Bombers
Probable Mission | -- | -- | -- | -- | -- | --
How Contacted | S | P | P | P | P | P
Initial Range | 8 Mi. | 7 Mi. | 4 Mi. | 8 Mi. | 8 Mi. | 12 Mi.
Elevation Angle | 3° | 2° | 2° | 2° | 2° | 3°
Range & Relative | ND | ND | ND | ND | ND | ND
Bearing of Plane
When it Detected
S/M
State (Beau.) | 2 | 3 | 3 | 3 | 3 | 3
Sea Direction (Rel.) | 230° | 300° | 090° | 090° | 090° | 280°
Visibility (Mi.) | 10 | Unltd. | Unltd. | Unltd. | Unltd. | Unltd.
Clouds( Height (Ft.) | 350 | 2,500 | 3,000 | 3,000 | 3,000 | 3,000
% Overcast | 65 | 30 | 20 | 20 | 25 | 2
M Bearing (Rel.) | Beneath | -- | -- | -- | -- | --
Angle | the | -- | -- | -- | -- | --
% Illuminated | Clouds | -- | -- | -- | -- | --

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— page 32 —
CONFIDENTIAL
U.S.S. THREADFIN (SS410)

(G) AIRCRAFT CONTACTS:

| | 49 | 50 | 51 | 52 | 53 | 54 |
|---|---|---|---|---|---|---|
| Contact Number | | | | | | |
| Date | 1/25 | 1/25 | 1/25 | 1/25 | 1/25 | 1/26 |
| S U B M A R I N E | Time | 1342(I) | 1348(I) | 1509(I) | 1540(I) | 1558(I) | 0900(I) |
| | Position: Lat. (N) | 33-13 | 33-13 | 33-11 | 33-10 | 33-09 | 33-24 |
| | Position: Long. (E) | 134-15 | 134-15 | 134-15 | 134-15 | 134-16 | 135-38 |
| | Speed (knots) | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 |
| | Trim | Subm. | Subm. | Subm. | Subm. | Subm. | Subm. |
| | Min. Since Last SD Radar Search | Subm. | Subm. | Subm. | Subm. | Subm. | Subm. |
| A I R C R A F T | Number | 1 | 9 | 1 | 1 | 3 | 1 |
| | Type | Betty | Bombers | Nate | Betty | Unk. | Jake |
| | Probable Mission | -- | -- | -- | -- | -- | -- |
| | How Contacted | P | P | P | P | P | P |
| | Initial Range | 4 Mi. | 12 Mi. | 5 Mi. | 4 Mi. | 4 Mi. | 6 Mi. |
| | Elevation Angle | 3° | 3° | 3° | 3° | 3° | 2° |
| | Range & Relative Bearing of Plane When It Detected S/M | ND | ND | ND | ND | ND | ND |
| C O N D I T I O N S | State (Beau. Sea) | 3 | 3 | 2 | 2 | 3 | 3 |
| | Direction (Rel.) | 280° | 280° | 280° | 280° | 115° | 030° |
| | Visibility (Mi.) | Unltd. | Unltd. | Unltd. | Unltd. | Unltd. | Unltd. |
| | Height (Ft.) | 3,000 | 3,000 | 3,000 | 3,000 | 3,000 | 3,000 |
| | Clouds (% Overcast) | 2 | 2 | 2 | 2 | 30 | 50 |
| | M Bearing (Rel.) | -- | -- | -- | -- | -- | -- |
| | O Angle | -- | -- | -- | -- | -- | -- |
| | % Illuminated | -- | -- | -- | -- | -- | -- |

- 31 -

— page 33 —
CONFIDENTIALL
U.S.S. THREADFIN (SS410)

(G) AIRCRAFT CONTACTS:

| | 55 | 56 | 57 | 58 | 59 | 60 |
|---|---|---|---|---|---|---|
| Contact Number | | | | | | |
| Date | 1/26 | 1/26 | 1/26 | 1/26 | 1/27 | 1/27 |
| Time | 1027(I) | 1232(I) | 1301(I) | 1940(I) | 1034(I) | 1545(I) |
| Position: Lat. (N) | 33-25 | 33-26 | 33-26 | 33-16 | 33-28 | 33-20 |
| Long. (E) | 135-40 | 135-38 | 135-37 | 135-23 | 135-30 | 135-18 |
| Speed (knots) | 1.5 | 1.5 | 1.5 | 0.5 | 1.5 | 3 |
| Trim | Subm. | Subm. | Subm. | Surf. | Subm. | Subm. |
| Min. Since Last | | | | | | |
| SD Radar Search | Subm. | Subm. | Subm. | N.U. | Subm. | Subm. |
| Number | 1 | 1 | 1 | 1 | 1 | 1 |
| Type | Pete | Unk. | Unk. | Rufe | Jake | Betty |
| Probable Mission | Patrol | -- | -- | Patrol | Patrol | -- |
| How Contacted | P | P | P | S | P | P |
| Initial Range | 2 Mi. | 10 Mi. | 7 Mi. | 2 Mi. | 8 Mi. | 3 Mi. |
| Elevation angle | 16° | 1° | 2° | 40° | 4° | 4° |
| Range & Relative | | | | 2 Mi. | | |
| Bearing of Plane | ND | ND | ND | 240° | ND | ND |
| When It Detected | | | | | | |
| S/M | | | | | | |
| State (Beau. Sea) | 3 | 3 | 3 | 4 | 3 | 4 |
| Direction(Rel.) | 300° | 210° | 210° | 040° | 270° | 095° |
| Visibility (Mi.) | Unltd. | Unltd. | Unltd. | Unltd. | Unltd. | Unltd. |
| Height(Ft) | 3,000 | 3,000 | 3,000 | 3,000 | 3,000 | 3,000 |
| Clouds(% Overcast) | 20 | 30 | 30 | 8 | 5 | 7 |
| Bearing (Rel.) | -- | -- | -- | 200° | -- | -- |
| Angle | -- | -- | -- | 200° | -- | -- |
| N % Illuminated | -- | -- | -- | 90% | -- | -- |

- 32 -

— page 34 —
CONFIDENTIAL
J.S.S. THREADFIN (SS410)

(G) AIRCRAFT CONTACTS:

Contact Number                               | 61      | 62      | 63      | 64      | 65      | 66
S   Date                                     | 1/28    | 1/28    | 1/28    | 1/29    | 1/30    | 1/30
U   Time                                     | 0945(I) | 1315(I) | 1406(I) | 1053(I) | 0700(I) | 1018(I)
B   Position: Lat. (N)                       | 33-11   | 33-13   | 33-14   | 33-27   | 33-28   | 33-20
M   Long. (E)                                | 134-14  | 134-14  | 134-15  | 135-30  | 135-32  | 135-30
A   Speed (knots)                            | 1.5     | 1.5     | 1.5     | 1.5     | 2       | 1.5
R   Trim                                     | Subm.   | Subm.   | Subm.   | Subm.   | Subm.   | Subm.
I   Min. Since Last                          |         |         |         |         |         |
N   SD Radar Search                          | Subm.   | Subm.   | Subm.   | Subm.   | Subm.   | Subm.
E   Number                                   | 1       | 1       | 1       | 1       | 1       | 1
    Type                                     | Unk.    | Jake    | Mavis   | Unk.    | Rufe    | Unk.
A   Probable Mission                         | Patrol  | Patrol  | Patrol  | --      | Patrol  | Patrol
I   How Contacted                            | P       | P       | P       | --      | P       | P
R   Initial Range                            | 8 Mi.   | 3 Mi.   | 8 Mi.   | 10 Mi.  | 4 Mi.   | 10 Mi.
C   Elevation angle                          | 2°      | 3°      | 2°      | 2°      | 3°      | 2°
R   Range & Relative                         |         |         |         |         |         |
A   Bearing of Plane                         |         |         |         |         |         |
F   When it Detected                         |         |         |         |         |         |
T   S/M                                      | ND      | ND      | ND      | ND      | ND      | ND
    Sea State (Beau.)                        | 2       | 1       | 1       | 2       | Calm    | Calm
C   Direction (Rel.)                         | 000°    | 160°    | 160°    | 310°    | 310°    | 310°
O   Visibility (Mi.)                         | Unltd.  | Unltd.  | Unltd.  | Unltd.  | Unltd.  | Unltd.
N   Height (Ft.)                             | 4,000   | 4,000   | 4,000   | 3,500   | 3,500   | 3,500
D   Clouds (% Overcast)                      | 3       | 1       | 1       | 40      | 70      | 70
I   Bearing (Rel.)                           | --      | --      | --      | --      | --      | --
T   Angle                                    | --      | --      | --      | --      | --      | --
I   % Illuminated                            | --      | --      | --      | --      | --      | --
O
N
S

- 33 -

— page 35 —
CONFIDENTIAL
U.S.S. THREADFIN (SS410)

(G) AIRCRAFT CONTACTS:

Contact Number | 67 | 68 | 69 | 70 | 71 | 72
Date | 1/30 | 1/30 | 1/31 | 2/1 | 2/2 | 2/4
S | Time | 1630(I) | 1655(I) | 1138(I) | 1035(I) | 1508(I) | 1410(I)
U | | | | | | |
B | Position: Lat. (N) | 33-16 | 33-17 | 33-11 | 32-33 | 32-23 | 31-53
M | | | | | | |
A | Long. (E) | 135-24 | 135-22 | 134-15 | 133-32 | 133-37 | 134-48
R | | | | | | |
I | Speed (knots) | 1.5 | 1.5 | 1.5 | 2 | 12 | 9.5
N | | | | | | |
E | Trim | Subm. | Subm. | Subm. | Subm. | Surf. | Surf.
  | Min. Since Last | Subm. | Subm. | Subm. | Subm. | 20" | 15"
  | SD Radar Search | | | | | |
  | Number | 1 | 1 | 1 | 1 | 1 | 6
A | Type | Cherry | Rufe | Betty | Zeke | Jake | B-29
I | | | | | | |
R | Probable Mission | -- | -- | -- | -- | Patrol | Bombing
C | | | | | | | Mission
R | How Contacted | P | P | P | P | S | S
A | | | | | | |
F | Initial Range | 10Mi. | 6 Mi. | 1.5Mi. | 6 Mi. | 6 Mi. | 10Mi.
T | | | | | | |
  | Elevation Angle | 2° | 3° | 10° | 2° | 4° | 3°
  | Range & Relative | ND | ND | ND | ND | ND | ND
  | Bearing of Plane | | | | | |
  | When it Detected | | | | | |
  | S/M | | | | | |
C | State (Beau.) | Calm | Calm | 3 | 6 | 4 | 2
O | | | | | | |
N | Sea( Direction(Rel.) | 310° | 310° | 010° | 010° | 100° | 290°
D | | | | | | |
I | Visibility (Mi) | Unltd. | Unltd. | Unltd. | 3 Mi. | 10 Mi. | 12Mi.
T | | | | | | |
I | Clouds( Height(Ft.) | 3,500 | 3,500 | 5,000 | 1,000 | 2,500 | 3,000
O | | % Overcast | 70 | 80 | 90 | 100 | 80 | 70
N | | | | | | |
S | Bearing (Rel.) | -- | -- | -- | -- | -- | --
  | Angle | -- | -- | -- | -- | -- | --
  | % Illuminated | -- | -- | -- | -- | -- | --

- 34 -

— page 36 —
CONFIDENTIAL
U.S.S. THREADFIN (SS410)

(G) AIRCRAFT CONTACTS:
                                  73        74        75        76        77        78
Contact Number
Date                              2/4       2/6       2/6       2/7       2/7       2/9
S U B M A R I N E
Time                              1425(I)   0850(I)   1400(I)   0755(I)   1214(I)   1145(I)
Position: Lat. (N)                31-55     33-28     33-27     33-30     33-31     29-31
           Long. (E)              134-48    135-24    135-30    135-26    135-27    140-30
Speed (knots)                     9.5       3         1.5       1.5       1.5       10.5
Trim                              Surf.     Subm.     Subm.     Subm.     Subm.     Surf.
Hr. Since Last
SD Radar Search                   Contact   Subm.     Subm.     Subm.     Subm.     10#
A I R C R A F T
Number                            6         1         1         1         1         1
Type                              B-29      Unk.      Navis     Jake      Unk.      Jake
Probable Mission                  Bombing   Patrol    Patrol    Patrol    --        Patrol
How Contacted                     SD        P         P         P         P         S
F I R S T
Initial Range                     9-18      6 Mi.     3 Mi.     2.5 Mi.   12 Mi.    4 Mi.
Elevation Angle                   --        2°        3°        4°        4°        3°
Range & Relative
Bearing of Plane
When it Detected
S/M                               ND        ND        ND        ND        ND        ND
C O N D I T I O N S
State (Beau.)                     3         2         2         3         3         7
Sea (Direction(Rel.)              290°      290°      230°      Calm      Calm      230°
Visibility (Mi.)                  12 Mi.    15 Mi.    15 Mi.    6 Mi.     1 Mi.     10 Mi.
Clouds (Height(Ft.)               3,000     3,000     6,500     1,000     100       50
         % Overcast               70        30        70        100       100       100
M Bearing (Rel.)                  -
O Angle                           -
N % Illuminated                   - 35 -

— page 37 —
CONFIDENTIAL
U.S.S. THREADFIN (SS410)
(G) AIRCRAFT CONTACTS:

Contact Number | 79 | 80
Date | 2/10 | 2/10
Time | 0805(K) | 0835(K)
Position: Lat. (N) | 29-49 | 29-49
Long. (E) | 144-09 | 144-14
Speed (knots) | 10.5 | 10.5
Trim | Surf. | Surf.
Min. Since Last | 15" | 10"
SD Radar Search
Number | 1 | 1
A | Type | Betty | Unk.
I | Probable Mission | Patrol | Patrol
R | How Contacted | S | S
C | Initial Range | 7 Mi. | 5 Mi.
R | Elevation Angle | 1° | 2°
A | Range & Relative | ND | ND
F | Bearing of Plane
T | When it Detected
  | S/M
C | Sea State (Beau.) | 7 | 7
O | Direction (Rel.) | 230° | 230°
N | Visibility (Mi.) | 10 Mi. | 7 Mi.
D | Height (Ft.) | 3,500 | 3,500
I | Clouds % Overcast | 50 | 50
T | Bearing (Rel.) | -- | --
I | Angle | -- | --
O | % Illuminated | -- | --
N
S

- 36 -

— page 43 —
U.S.S. THREADFIN (SS410)

CONFIDENTIAL
Subject: U.S.S. THREADFIN - Report of War Patrol No. ONE.

One and a half hours after an attack near ICHIE
S.KI, five additional anti-submarine vessels joined in
the search for us apparently coming from the small craft
base at OSHIMA.

Dozens of sampans, both sailing and power driven,
were seen within ten miles of the beach. None were
doing anything suspicious. Most of them fished by
trolling from a pair of bamboo outrigger poles about 20'
long. These might be the radio antennas previously re-
ported.

ESCORTS:

Nothing new. Escorts for coastal traffic varied
from 50's to 500 ton M.Y.'s. Some echo ranged, some did
not.

R.D.R:

All prominent points of land in areas SIX, SEVEN,
and EIGHT had low frequency search radar. Whether they
were for aircraft or surface search is not known.
Normally we kept ten miles clear of their positions when
on the surface. If we steadied our SJ in their direction
for a minute or two there was a definite tendency for
them to stop sweeping and steady near our bearing.
Nothing unusual ever developed subsequent to these
incidents.

EVASION:

Evasion consisted of going deep and running silent-
ly. It is believed that at no time was our location too
accurately known to anti-submarine vessels. Search after
attacks was persistent but ineffective.

(K) MAJOR DEFECTS - (HULL):

1. While being depth charged on 30 January, a bad leak
occurred in the cross connection between the compensat-
ing line and the main motor cooling system. Because of
inaccessibility, the exact cause cannot be determined
until refit. However, it is believed to have been caused
by insufficient clearance between it and the flexibly
shock mounted control cubical - the movement of the
cubical during depth charging striking and damaging the
line. It is extremely fortuitous that the casualty was
no worse, as it could have been disastrous.

- 42 -

— page 45 —
CONFIDENTIAL
U.S.S. THREADFIN (SS410)
Subject: U.S.S. THREADFIN - Report of War Patrol No. ONE.

The cause of the explosion was insufficient natural
ventilation prior to the introduction of hydrogen burner
loads to discharge a low cell. A roll of the ship pull-
ed one lead clear causing the necessary spark and sub-
sequent explosions.

No replacement cell caps were available so torpedo
was kept in a last priority status for the remainder of
the patrol.

Ship's charging orders have been clarified and re-
vised to prevent a similar occurrence.

3. On 4 February 1945, the 40 mm. failed to fire. The
automatic loader would not function. The plunger (L222
564) and pawl (L222648) were frozen and would not allow
the star wheels to turn. It is impossible to grease
this part without removing the loader. Apparently it
will be necessary to remove the automatic loader weekly
and clean and grease it. This is a heavy, awkward job -
particularly during darkness.

4. On 4 February 1945, the 20 mm. failed after three
rounds. This was caused by maladjustment of the handle
bar firing lever which would not allow the trigger to
return to its full forward position. We now know that
this adjustment varies with the gun mounted.

(L) RADIO:

Although J.P. jamming was present on all submarine
frequencies about 70% of the time, it did not prevent
copying or clearing all pertinent messages. All types
of jamming were experienced but a steady CW note seem-
ed to predominate.

The area frequency was usually cluttered with J.P.
voice, CW and/or MCW.

The performance of the RBH receiver is not up to
the standard of that of the R.L. It does not tune out
jamming as effectively for either voice or CW. The
R.O. provided as an entertainment receiver, is a better
receiver along those lines than the RBH.

(M) RADAR:

SD-5 (With Long Persistant Screen):

In general the operation of the SD was unsatisfactory.

- 44 -

— page 51 —
CONFIDENTIALL
U.S.S. THREADFIN (SS410)
Subject: U.S.S. THREADFIN - Report of War Patrol No. ONE.

On the other end of the scale, it didn't distinguish a
submarine from force five seas at about 3,000 yards
with ten feet of periscope exposed. One disadvantage
with the present installation is the number of units
common to both SJ and ST. Decommissioning one for
routine or emergency work almost always decommissions
the other. It is suggested that the replacement for
the SJ (SV?) be a separate and distinct unit from the
ST in order to have the appropriate day or night radar
ready for use.

5. In addition to the very useful capability of the
ST in giving accurate masthead heights, the use of the
horizontal telemeter scale coupled with angle on the
bow gives an excellent ship length. This tended to be
a disillusioning in our case. The largest ship
we saw moving along the coast was no bigger than 2,500
tons.

6. The optical qualities of the ST periscope were so
far superior to those of the attack periscope that the
latter was seldom used.

7. The large temperature differential between the
waters in or near the KURI SHIO and the winter air caus-
ed periscope fogging shortly after either periscope was
raised. Towards the end of the patrol we could count on
periscopes fogging to the point of uselessness in less
than thirty seconds after exposure.

8. We carried Ik. XVIII's forward torpedo. It
was the first experience anyone aboard had had with this
torpedo and we learned about them the hard way - one
minor battery explosion and one flooded afterbody. The
commanding officer is certainly impressed with their
wakeless feature, but can't help but wish they would go
faster to give more target speed coverage.

9. Upon commissioning of the THREADFIN, one junior
officer, three CPO's, and a handful of men had held the
same job in a previous ship. The remainder had just
floated up from lesser jobs. 70% had never made a war
patrol. The competent manner in which all hands learned
their jobs, took over a new ship, trained, and three
months later conducted themselves on a war patrol is a
source of much gratification and pride to the commanding
officer. All are deserving of the highest praise.

- 50 -

— page 52 —
SUBMARINE DIVISION THREE TWENTY ONE

FB5-321/A16-1                                       Care of Fleet Post Office,
                                                    San Francisco, California.
Serial (014)                                        17 February 1945

C-O-N-F-I-D-E-N-T-I-A-L

FIRST ENDORSEMENT to
THREADFIN Report of
First War Patrol.

From:        The Commander Submarine Division THREE TWENTY-ONE.
To :         (1) The Commander-in-Chief, U. S. Fleet.
Via :        (2) The Commander Submarine Squadron THIRTY-TWO.
             (3) The Commander Submarine Force, U. S. Pacific Fleet.
             (3) The Commander-in-Chief, U. S. Pacific Fleet.

Subject:     U.S.S. THREADFIN (SS 410) - Report of First War Patrol.

             1. The first war patrol of the THREADFIN, conducted in
the Empire Area north of Lat. 30°N and west of Long. 136°E, was of
54 days duration with 30 days in the area. Weather was bad through-
out.

             2. In addition to eighty aircraft contacts, numerous
fishing craft, sampans, and patrols, there were six contacts worthy
of torpedo fire of which one was a properly marked hospital ship.
Life guard duties were performed, but no rescue opportunities arose.

             3. On 30 January 1945, while conducting submerged patrol,
a PC type patrol was sighted conducting an A/S sweep. This vessel
was followed shortly by a small coastal freighter, similar to
TAIHOSAN MARU (EU) - 1800T, with two PC escorts to seaward and a
rufe patrolling overhead. THREADFIN was unable to close inside of
3000 yards, so to insure hitting, six electric torpedoes were
fired on a 120° starboard track, using a spread coverage of 700
feet. One hit obscured the target in smoke and steam, and it evidentl
sank immediately. Deep submergence was forced by a close escort
and the air screen, but only random depth charging followed. While
seeking 450', shortly after a sounding indicated 90 fathoms under
the keel, THREADFIN struck bottom at 462'. One sound head was
damaged. A ruptured main motor cooling cross connection presented
a problem that was ably handled.

             4. On 1 February 1945 an RO-60 class submarine zigged
away just before a submerged attack could be delivered, and a
satisfactory range could not be attained.

             5. On 6 February 1945 two freighters with 3 escorts
were sighted close inshore and could not be closed. Next day an
approach was made on what was thought to be a small AK which was
finally identified as a 150 foot converted patrol vessel. THREADFIN

                                     -1-

— page 53 —
FB5-321/A16-1
Serial (014)

Subject: U.S.S. THREADFIN (SS 410) - Report of First War Patrol.

went deep when this vessel turned toward at 1400 yards, but no
attack developed. On returning to periscope depth one half hour
later the CO was chagrined to find that 2 AK's and 2 escorts had
slipped by and were out of range.

6. On 13 February 1945 six electric torpedoes were fired
with a 600' spread at an AM#13 class (EC) from 2500 yards with
excellent data for 0 disheartening misses. Torpedoes probably
underran.

7. THREADFIN returned from patrol clean, smart, and in
good material condition. Normal refit by PELIAS and Submarine
Division THREE TWENTY-TWO Relief Crew is indicated.

8. The Commanding Officer, officers and crew of the
THREADFIN are congratulated on the completion of this strenuous
patrol and on the damage inflicted.

[SIGNATURE: J. R. Waterman]
J. R. WATERMAN

— page 54 —
FC5-32/A16-3
Serial: (017)

SUBMARINE SQUADRON THIRTY-TWO
Care of Fleet Post Office
San Francisco, California

22 February 1945

C-O-N-F-I-D-E-N-T-I-A-L

SECOND ENDORSEMENT to
CO THREADFIN (SS410) Conf.
Ltr. Ser. (010) dated
16 February 1945.

From: The Commander Submarine Squadron THIRTY-TWO.
To : The Commander-in-Chief, United States Fleet.
Via : (1) The Commander Submarine Force, PACIFIC FLEET, Administration.
(2) The Commander-in-Chief, PACIFIC FLEET.

Subject: U. S. S. THREADFIN (SS410) - Report of First War Patrol.

1. Forwarded concurring in the thorough remarks of the Commander
Submarine Division THREE TWENTY-ONE.

2. It is recommended that the THREADFIN be credited with the
following:
SUNK
1 - Small AK (Taihosan Maru Type) 2000 Tons (Attack No. 1)

3. The Squadron Commander congratulates the Commanding Officer,
Officers, and crew of the THREADFIN upon completing this submarine's first
war patrol and on the damage inflicted upon the enemy.

[SIGNATURE: K. C. Hurd]
K. C. HURD

— page 55 —
FF12-10(A)/A16-3(18)
Serial 0447

CONFIDENTIAL

THIRD ENDORSEMENT to
THREADFIN Report of
First War Patrol.

COMSUBSPAC PATROL REPORT NO. 684
U.S.S. THREADFIN - FIRST WAR PATROL.

From: The Commander Submarine Force, Pacific Fleet.
To : The Commander-in-Chief, United States Fleet.
Via : The Commander-in-Chief, U.S. Pacific Fleet.

Subject: U.S. THREADFIN (SS410) - Report of First War
Patrol (25 December 1944 to 16 February 1945).

1. The first war patrol of the THREADFIN, under the
command of Commander J. J. Foote, U.S. Navy, was conducted in the
areas southeast of the Japanese Empire. Lifeguard duties were per-
formed as well as offensive patrol.

2. The THREADFIN on her first war patrol encountered
heavy enemy air anti-submarine measures. Numerous surface contacts
were made, most of which were small craft. Two torpedo attacks were
delivered. One resulted in the sinking of a small AK, and the other,
made on a small minesweeper, unfortunately was unsuccessful.

3. Award of Submarine Combat Insignia for this patrol
is authorized.

4. The Commander Submarine Force, Pacific Fleet, con-
gratulates the commanding officer, officers, and crew of the THREADFIN
on this successful first war patrol. The THREADFIN is credited with
having inflicted the following damage upon the enemy:

[STAMP: S U N K
[STAMP: Office of the Chief of Naval Operations
[STAMP: FLEET MAINTENANCE
[STAMP: MAR 1 5 1945
[STAMP: RECEIVED
[STAMP: NAVY DEPARTMENT]
1 - Small AK (EU) 2,000 tons (Attack No. 1)

DISTRIBUTION:
(Complete Reports)
Cominch
CNO
Cincpac
JICPOA
JICPOA
Comsrvpac
Cinclant
Comsubslant
S/M School, NL
CO, S/M Base, PH
Comsopac
Comsowespac
Comsubsowespac
CTG 71.9
Comnorpac

SUBMARINE FORCE, PACIFIC FLEET
Care of Fleet Post Office;
San Francisco, California,
9 March 1945.

NOTE: THIS REPORT WILL BE
DESTROYED PRIOR TO
ENTERING PATROL AREA.

J. H. BROWN, Jr.,
Deputy ComSubSpac.

59 | (7) [HANDWRITTEN: (5)]
   | (5) [HANDWRITTEN: (6)] Comsubspac
   | (1) Comsubspac/d
   | (1) SUBAD, NI
   | (1) ComsubspacSubordcom
   | (1) All Squadron and Div.
   | (3) Commanders, Pacific
   | (2) Substrainpac
   | (1) All Submarines, Pacific
   | (2)
   | (1) [SIGNATURE: E. L. Hynes]
   | (2) E. L. HYNES, 2nd,
   | (2) Flag Secretary.
   | (1)

[HANDWRITTEN: (3)]
[HANDWRITTEN: (40)]
[HANDWRITTEN: (2)]
[STAMP: RECEIVED S-C FILES]
[HANDWRITTEN: (2) Room 2056]
[HANDWRITTEN: (2) 14 MAR 1945]
[HANDWRITTEN: (2) File No. (ou)/A16-3/23/SS410]
[HANDWRITTEN: (1) No. 159411]
[HANDWRITTEN: (1)]
[HANDWRITTEN: (1)]

— page 56 —
[UNCLEAR: illegible text]
[UNCLEAR: illegible text]
[UNCLEAR: illegible text]
[UNCLEAR: illegible text]

— page 57 —
SS410/A16-3

Serial: 0153

[STAMP: DECLASSIFIED]
[STAMP: CONFIDENTIAL] (crossed out)

From: The Commanding Officer.
To : The Commander in Chief, United States Fleet.
Via : Official Channels.

Subject: U.S.S. THREADFIN (SS 410), Report of War Patrol number TWO.

Enclosures: (A) Subject report.
(B) Track Chart. (For ComSubSPac only)

1. Enclosure (A), covering the SECOND war patrol of this vessel
conducted in Southern Empire Waters during the period 14 March 1945 to 4 May 1945,
is forwarded herewith.

U.S.S. THREADFIN (SS 410)

Care of Fleet Post Office,
San Francisco, California.
4 May 1945.

DECLASSIFIED-ART. 0445, OPNAVINST 5510.10
BY [HANDWRITTEN: G. M. G. K.] DATE [HANDWRITTEN: 6/24/72]

[SIGNATURE: J. J. FOOTE]
J. J. FOOTE

[HANDWRITTEN: FILMED]
[HANDWRITTEN: 122382]

— page 61 —
CONFIDENTIAL
Subject: U.S.S. THREADFIN - Report of War Patrol No. TWO.
U.S.S. THREADFIN (SS 410)

[HANDWRITTEN: 25] March 1945:
0200 Patrolled on lifeguard station.
0200 Strike completed. No information on whether or not any planes down.
0535 Submerged. Patrolled near lifeguard station off southwest approaches to TOKYO BAY. - Ran at 50' and copied scheds on SD mast waiting for a release from station. Now diving officers and planesmen really needed practice.
1150 Sighted a pair of fishing sampans, bearing 098°(T), five miles, on a southwesterly course.
1200 Latitude: 33°-38' N. Longitude: 138°-45' E.
1250 Sampans no longer in sight.
1805 Surfaced.

26 March 1945:
0005 Received orders to head west for lifeguard duties off KII SUIDO.
0005 Set course for new station.
1200 Latitude: 32°-25' N. Longitude: 136°-22' E.
1206 Sighted a [UNCLEAR: DUMMY] bearing 240°(T), 10 miles, on an easterly course. Submerged.
1230 Surfaced.
1630 Received orders to join CO-ORDINATED ATTACK GROUP 24, consisting of [UNCLEAR: USS] (SS 410), TRIGGER, and THREADFIN - and to proceed at best speed to stations south of the BUNGO SUIDO.
1740 Proceeded at four engine speed.
1740 -Acknowledged receipt of orders - THREADFIN Serial THREE.

27 March 1945:
0200 Enroute new station at four engine speed.
0200 On station. Commenced east-west patrol.
0545 Submerged.
0605 Surfaced to investigate possible pinging bearing 180°(T).
0605 Proceeded down bearing at two engine speed, slowing periodically to listen.
0643 Still no we were listening to porpoises. Bearing jumping erratically.
0710 Submerged. Ran at 50' maintaining watch on area frequency.
1200 Latitude: 31°-56' N. Longitude: 132°-22' E.
1623 Sighted an unidentified landplane, bearing 340°(T), eight miles, on a westerly course.
1730 Surfaced. Overcast. Commenced closing KYUSHU for a fix.
1735 Sighted a floating mine and destroyed it with 20mm fire.
1735 Lat. 32°-06' N. Long. 132°-11' E.
1757 Sighted an unidentified aircraft, bearing 289°(T), four miles, on northerly course. Submerged.

- 4 -

— page 62 —
U.S.S. THREADFIN (SS 410)

CONFIDENTIAL
Subject: U.S.S. THREADFIN. Report of War Patrol No. TWO.

1825 Surfaced.
2010 Obtained fix. 42 miles from our DR. Set course for patrol
position.
2250 Heard engine and then sighted unidentified single engine plane
overhead on northwesterly course.
2306 Submerged.
2325 Heard engines and then sighted an unidentified twin engine plane,
distance one mile. Submerged.
2347 Surfaced. APR gave us the usual warning of these planes but SJ
and SD radars missed them completely.

28 March 1945:

0045 Patrolled approaches to the Bungo Suido.
0046 Heard plane in the neighborhood.
0055 SD contact three miles closing. Submerged.
0150 Surfaced.
0450 Set course for patrol off east coast of KYUSHU.
0610 Sighted an unidentified plane bearing 350°(T), six miles, on
southerly course. Submerged.
0650 Surfaced. Proceeded on four main engines.
0850 Submerged 24 miles northeast of TOI MISAKI. Closed coast to the
100 fathom curve.
1200 Latitude: 31°-36' N. Longitude: 131°-41' E.
1440 Sighted an unidentified land plane bearing 257°(T), 12 miles.
1535 Sighted an unidentified aircraft bearing 300°(T), 9 miles.
1558 Sighted mast bearing 028°(T), seven miles. Commenced approach(SC#1)
1610 Two masts in sight. Looked like a pair of destroyers.
1613 ST ranging 8500 and 9000 yards, giving each a masthead height of
65 feet.
1616 Echo ranging from contacts. Contacts identified as two DE's of
UN-1 Class, zigzagging on base course 190°(T), speed 14 knots.
One was stationed about 1200 yards abeam and a little aft of
the nearest.
1623 In nice position to fire forward at left hand DE, and aft at right
hand DE, if they maintained course.
1627 (Approx) Sound reported two additional sets of similar screws to the north-
ward. Not seen with limited periscope exposure required at this
stage of the game.
1628 Targets zigged right leaving us broadside to right hand DE, range
under 1000 yards, angle on the bow nearly zero. Left target range
1500 yards, angle on the bow sixty port.
1629 Commenced firing full nest forward at left hand DE, depth four
feet, 600' spread, torpedo run 1200 yards. That should be enough
to insure hits regardless of torpedo depth performance and target
maneuvers. Started down on third torpedo as the DE 800 yards on
our starboard beam was closing with disconcerting rapidity, no
change in angle on the bow.

5

— page 82 —
CONFIDENTIAL

U. S. S. THREADFIN (SS 410)
REPORT OF WAR PATROL NUMBER TWO

(F) SHIP CONTACTS

No. | Time | Date | Lat. (N) | Long. (E) | Type(s) | Initial Range | Est. C & S | How Contacted | Remarks
----|------|------|||||||
1   | 1558 | 3/28 | 31°-49.5' | 131°-44.0' | Two Trawlers, and four luggers | 10,000 | 190°(T) 14 kts. | P | Patrolling 100 fathom curve.
2   | 2005 | 3/28 | 31°-50.0' | 132°-15.0' | Two DE's, UN-1. | 14,000 | 015°(T) 8 kts. | Lookout | Small craft convoy.
3   | 1710 | 4/1 | 32°-32.0' | 132°-02.0' | One SC. | 10,800 | 200°(T) 10 kts. | P | Patrolling
4   | 1508 | 4/6 | 32°-42.1' | 131°-58.0' | Two FF's. | Six miles | 200°(T) 13 kts. | Sound | Patrolling prior to sortie.
5   | 1647 | 4/6 | 32°-43.5' | 131°-59.0' | Two Tug type Mine Sweeps | 8,500 | 200°(T) 6 kts. | P | Sweeping prior to sortie.
6   | 1926 | 4/6 | 32°-42.8' | 131°-59.0' | Two large warships, and six escorts. | 11,000 | 140°(T) 22 kts. | Sound, Radar. | Task Force

- 25 -

— page 93 —
CONFIDENTIAL
U.S.S. THREADFIN (SS 410).
Subject: 'U.S.S. THREADFIN - Report of War Patrol No. TWO.

— page 98 —
FC5-4/A16-3
Serial: 0356
C-O-N-F-I-D-E-N-T-I-A-L
FIRST ENDORSEMENT TO:
USS THREADFIN (SS410)
Report of Second
War Patrol.

From: Commander Submarine Squadron FOUR.
To: Commander-in-Chief, U.S. FLEET.
Via: (1) Commander Submarine Force, PACIFIC FLEET, Admin.
(2) Commander-in-Chief, U.S. PACIFIC FLEET.

Subject: USS THREADFIN (SS410) - Report of Second War Patrol.

1. The second war patrol of the USS THREADFIN was con-
ducted in Southern Empire waters during the period 14 March to
4 May 1945.

2. On 26 March, THREADFIN was ordered to join a coor-
dinated attack group, consisting of SEA DOG, TRIGGER and herself,
with the Group Commander in the SEA DOG. This was disbanded on
31 March and THREADFIN ordered to form another coordinated attack
group, consisting of SILVERSIDES, HACKLEBACK, and herself, with
the Group Commander in the SILVERSIDES. The primary mission of
this second attack group was to prevent undetected enemy task
force sorties from vicinity of BUNGO SUIDO. During these periods
lifeguard duties were performed.

Attacks were as follows:

Torpedo Attack No. 1: On the afternoon of 28 March THREADFIN
made a submerged attack on a pair of
destroyer escorts 1,200 yards apart in line of bearing. Six
MK 18-1 torpedoes were fired at one escort, range 1,500 yards,
75° port track, gyros 010°, speed used 14 knots, 2° divergent
spread applied for each torpedo, depth set 4 feet. One timed
hit was obtained, target screws stopped. Went deep, as depth
charging commenced. The ST periscope was used for ranges and
checking masthead height on initial set-up.

Gun Attack No. 1: Later on during the night of 28 March,
at 2312, a battle-surface gun attack was
made on five units of a small-craft convoy, consisting of two
small trawlers and four luggers in column; average firing
range 1,500 to 2,800 yards, enemy speed 8 knots. It was es-
timated damage was done to three luggers and two small trawlers.

3. On 6 April, at 1944, an important enemy task force
was contacted just off FUKA SHIMA. It is regretted that high speed
and radical zigzagging of this valuable target group was such as to

- 1 -
SUBMARINE SQUADRON FOUR
Fleet Post Office, 11/rg
San Francisco, Calif.,
10 May 1945.

— page 99 —
11/rg

FC5-4/A16-3
SUBMARINE SQUADRON FOUR
Fleet Post Office,
Serial: 0356
San Francisco, Calif.,
10 May 1945.
C-O-N-F-I-D-E-N-T-I-A-L
SUBJECT: USS THREADFIN (SS410) - Report of Second War Patrol.

— page 102 —
[UNCLEAR: 10]

| DATE | TIME | LATITUDE | LONGITUDE | COURSE | SPEED | REMARKS |
|---|---|---|---|---|---|---|
| 19 | 0000 | 35-12N | 125-45E | 270 | 10 | On patrol in assigned area. Weather clear, sea calm. Visibility good. No contacts. |
| 19 | 0400 | 35-12N | 125-45E | 270 | 10 | On patrol in assigned area. Weather clear, sea calm. Visibility good. No contacts. |
| 19 | 0800 | 35-12N | 125-45E | 270 | 10 | On patrol in assigned area. Weather clear, sea calm. Visibility good. No contacts. |
| 19 | 1200 | 35-12N | 125-45E | 270 | 10 | On patrol in assigned area. Weather clear, sea calm. Visibility good. No contacts. |
| 19 | 1600 | 35-12N | 125-45E | 270 | 10 | On patrol in assigned area. Weather clear, sea calm. Visibility good. No contacts. |
| 19 | 2000 | 35-12N | 125-45E | 270 | 10 | On patrol in assigned area. Weather clear, sea calm. Visibility good. No contacts. |
| 20 | 0000 | 35-12N | 125-45E | 270 | 10 | On patrol in assigned area. Weather clear, sea calm. Visibility good. No contacts. |
| 20 | 0400 | 35-12N | 125-45E | 270 | 10 | On patrol in assigned area. Weather clear, sea calm. Visibility good. No contacts. |
| 20 | 0800 | 35-12N | 125-45E | 270 | 10 | On patrol in assigned area. Weather clear, sea calm. Visibility good. No contacts. |
| 20 | 1200 | 35-12N | 125-45E | 270 | 10 | On patrol in assigned area. Weather clear, sea calm. Visibility good. No contacts. |
| 20 | 1600 | 35-12N | 125-45E | 270 | 10 | On patrol in assigned area. Weather clear, sea calm. Visibility good. No contacts. |
| 20 | 2000 | 35-12N | 125-45E | 270 | 10 | On patrol in assigned area. Weather clear, sea calm. Visibility good. No contacts. |
| 21 | 0000 | 35-12N | 125-45E | 270 | 10 | On patrol in assigned area. Weather clear, sea calm. Visibility good. No contacts. |
| 21 | 0400 | 35-12N | 125-45E | 270 | 10 | On patrol in assigned area. Weather clear, sea calm. Visibility good. No contacts. |
| 21 | 0800 | 35-12N | 125-45E | 270 | 10 | On patrol in assigned area. Weather clear, sea calm. Visibility good. No contacts. |
| 21 | 1200 | 35-12N | 125-45E | 270 | 10 | On patrol in assigned area. Weather clear, sea calm. Visibility good. No contacts. |
| 21 | 1600 | 35-12N | 125-45E | 270 | 10 | On patrol in assigned area. Weather clear, sea calm. Visibility good. No contacts. |
| 21 | 2000 | 35-12N | 125-45E | 270 | 10 | On patrol in assigned area. Weather clear, sea calm. Visibility good. No contacts. |
| 22 | 0000 | 35-12N | 125-45E | 270 | 10 | On patrol in assigned area. Weather clear, sea calm. Visibility good. No contacts. |
| 22 | 0400 | 35-12N | 125-45E | 270 | 10 | On patrol in assigned area. Weather clear, sea calm. Visibility good. No contacts. |
| 22 | 0800 | 35-12N | 125-45E | 270 | 10 | On patrol in assigned area. Weather clear, sea calm. Visibility good. No contacts. |
| 22 | 1200 | 35-12N | 125-45E | 270 | 10 | On patrol in assigned area. Weather clear, sea calm. Visibility good. No contacts. |
| 22 | 1600 | 35-12N | 125-45E | 270 | 10 | On patrol in assigned area. Weather clear, sea calm. Visibility good. No contacts. |
| 22 | 2000 | 35-12N | 125-45E | 270 | 10 | On patrol in assigned area. Weather clear, sea calm. Visibility good. No contacts. |

— page 103 —
SS410/A16-3

Serial: 0173
[STAMP: DECLASSIFIED]
[STAMP: CONFIDENTIAL]

From: The Commanding Officer.
To : The Commander-in-Chief, United States Fleet.
Via : Official Channels.

Subject: U.S.S. THREADFIN (SS 410) - Report of War Patrol No. THREE.

Enclosures: (A) Subject Report.
(B) Track Chart. (To ComSubSPac only)

1. Enclosure (A), covering the THIRD War Patrol of this vessel
conducted in SOUTHERN HONSHU WATERS and in the EAST CHINA and YELLOW SEAS
during the period 1 June 1945 to 28 July 1945 is forwarded herewith.

[HANDWRITTEN: FILMED]
[HANDWRITTEN: 136606] U.S.S. THREADFIN (SS 410)

Care of Fleet Post Office,
San Francisco, California.
28 July 1945.
[STAMP: DECLASSIFIED ART. 0445, OPNAVINST 5510.1C]
BY [HANDWRITTEN: J.J. Foote] DATE [HANDWRITTEN: 8/20/77]

[SIGNATURE: J. J. FOOTE]

— page 106 —
U.S.S. THREADFIN (SS 410)

CONFIDENTIAL

Subject: U.S.S. THREADFIN - Report of War Patrol No. THREE.
and are the different crops of this image to help you see better, use these only as hints:

U.S.S. THREADFIN (SS 410)

CONFIDENTIAL

Subject: U.S.S. THREADFIN - Report of War Patrol No. THREE.

— page 107 —
```
U.S.S. THREADFIN (SS 410)

CONFIDENTIAL
Subject: U.S.S. THREADFIN - Report of War Patrol No. THREE

23 June 1945:
0841  On lifeguard station. Latitude: 30°-00' N. Longitude: 140°-40' E.
0906  Submerged for unidentified SD plane contact at four miles.
1200  Surfaced. Many friendly planes contacted during the day.
       Latitude: 30°-02' N. Longitude: 140°-38' E.

24 June 1945:
0935  Patrolled near SOFU GAN.
       Submerged for unidentified plane bearing 000°(T), four miles, on a southerly course. Closed TORI SHIMA submerged.
1100  Commenced close reconnaissance of south side of TORI SHIMA, SEA ROBIN doing same to north. Only items of interest seen were two Type "M" landing barges (8 tons) hauled out on western beach.
       Latitude: 30°-25' N. Longitude: 140°-19' E.
1447  Surfaced five miles southeast of TORI SHIMA. Discussed the prospects of a bombardment and both agreed that prospective results would not be worth the ammunition expenditure. Departed company.
1635

25 June 1945:
0700  Patrolled near SOFU GAN.
       On lifeguard station. Latitude: 30° N. Longitude: 140°-40' E.
0800  Latitude: 29°-55' N. Longitude: 140°-37' E.
1400  Strike cancelled. Proceeded to westward for new lifeguard station.
1758  Sighted and destroyed a floating mine in Latitude: 29°-57' N., Longitude: 139°-56' E.
2322  Submerged for plane close aboard. Probably friendly.
2341  Surfaced.

26 June 1945:
0600  Enroute lifeguard station. Lat: 30° N. Long: 138°-25' E.
       On station. Many friendly planes contacted during the day.
0950  E-29 reported having sighted a life raft nearby. Commenced search under his directions. Strongly suspect he had seen whales in the spotter visibility as he was never able to keep them in sight for more than two circles. He dropped two sets of flares about five miles apart (where we found whales) and later reported life rafts in two other positions some thirty miles apart. Later in the day our DUBOOS searched the entire area, with negative results.
1200  Latitude: 29°-54' N. Longitude: 138°-37' E.
1500  Visibility, 500 yards - remained in position until visibility cleared fifteen hours later.
```

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U.S.S. THREADFIN (SS 410)

CONFIDENTIAL

Subject: U.S.S. THREADFIN - Report of War Patrol No. THREE.

— page 115 —
U.S.S. THREADFIN (SS 410)

CONFIDENTIAL

Subject: U.S.S. THREADFIN - Report of War Patrol No. THREE.

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U.S.S. THREADFIN (SS 410),

CONFIDENTIAL

Subject: U.S.S. THREADFIN - Report of War Patrol No. THREE.

— page 121 —
U.S.S. THREADFIN (SS 410)

CONFIDENTIAL
Subject: U.S.S. THREADFIN - Report of War Patrol No. THREE.

22 July 1945:
0015 SEA ROBIN in communication with us and in contact with two of the
     remaining SD's. We had very little 5" ammunition left, so set off
     a late start to clear AREAS NINE and TWELVE.
     Arranged to have Commander STIMSON in SEA ROBIN pass on all
     pertinent information to POMFRET concerning areas.
0125 Sighted gunfire bearing 290°(T), distance about 20 miles. SEA ROBIN
     at work.
0140 Explosion and burning ship sighted at 300°(T), 20 miles. One more
     SD'checked off.
0300 Sent THREADFIN Serial SIX to POMFRET and COMSUBSPAC via NPG suggest-
     ing POMFRET rendezvous with SEA ROBIN for area information. Also
     acknowledged orders to THREADFIN to depart area and proceed to GUAM.
0600 Sighted a floating mine.
0815 Two friendly search planes sighted. They had seen nothing.
1200 Latitude: 32°-11' N. Longitude: 128°-47' E.
1845 Was pleasantly surprised to sight the POMFRET bearing 201°(T), five
     miles distant. Thought she was a day ahead of this position.
     Closed and gave Commander HESS what information we had on the areas.
1948 Submerged for a RUFE sighted bearing 120°(T), four miles, on a
     northwesterly course.
2025 Surfaced.
2051 Sighted a friendly PV bearing 010°(T), six miles. Contacted him on
     VHF immediately as he was coming in to pass close aboard.
2158 Plane contact on SJ closing rapidly. Submerged. Range closed to
     3000 yards before we were under.
2222 Surfaced.

23 July 1945:
0000 Enroute GUAM.
0330 Commenced transit of COLNETT STRAIT.
     Transit completed. Entered AREA CORRIDOR.
1200 Sighted several friendly planes during the day.
     Latitude: 29°-12' N. Longitude: 132°-15' E.
1500 Transmitted THREADFIN Serial SEVEN to CTG 17.7 requesting noon
     rendezvous on the twenty-eighth.
2200 Received orders to increase speed slightly and arrive at GUAM
     rendezvous at dawn on the twenty-eighth.

24 July 1945:
     Enroute GUAM.
     Sighted many friendly planes during the day.
0532 Sighted SANDLANCE on her lifeguard station.
1200 Latitude: 29°-15' N. Longitude: 137°-45' E.
1920 Entered AREA NECK.
2213 Sighted and exchanged recognition with H.M.S. NAPIER (D-13).

- 18 -

— page 126 —
CONFIDENTIAL
U.S.S. THREADFIN (SS 410)
Subject: Report of War Patrol No. THREE.
(F) SHIP CONTACTS

| No. | Date | Time(I) | Lat. (N) | Long. (E) | Type(s) | Initial Range | Est. C & S | How Contacted | Remarks |
|---| SJ at night; | Lookout - day. | |
| 1 | 0100-1000 | 7-11 | 34°-35' | 120°-23' | 4 Chinese cargo junks | 8-10 miles | 10 kts. 090°(T) | High periscope | 190' long. |
| 2 | 0955 | 7-14 | 38°-42' | 120°-52' | Coastal freighter | 10 miles | 10 kts. 090°(T) | High periscope | Being used as an SC. |
| 3 | 1530 | 7-14 | 38°-43' | 121°-10' | Tug | 4 miles | Various | Periscope | Sunk by gunfire. |
| 4 | 1809 | 7-14 | 38°-36' | 121°-02' | 4 masted cargo junk | 10 miles | 4 kts 270°(T) | High periscope | Sunk by gunfire. |
| 5 | 1235 | 7-15 | 39°-31' | 123°-46' | 4 masted junk rigged cargo schooner | 10 miles | 4 kts 090°(T) | High periscope | Sunk by gunfire. |
| 6 | 0727 | 7-15 | 39°-30' | 123°-20' | 4 masted cargo junk | 11 miles | 4 kts 015°(T) | Periscope | Sunk by gunfire. |
| 7 | 1158 | 7-16 | 36°-40.8' | 126°-07' | 3 or 4 masted cargo schooner | 7 miles | 4 kts 130°(T) | Periscope | Each about 50' long. |
| 8 | 0500 | 7-18 | 126°-54' | 125°-07' | Six 2 masted junks | 5 miles | 5 kts 180°(T) | SJ Radar | Sunk by torpedoes. |
| 9 | 2218 | 7-19 | 34°-52' | 125°-25' | 1 Unidentified ship | 6 miles | 5 kts 000°(T) | SJ Radar | Destroyed two by gunfire. |
| 10 | 1244 | 7-20 | 33°-54.5' | 125°-39' | Two cargo schooners | 6 miles | 5 kts 060°(T) | Periscope | Destroyed two by gunfire. |
| 11 | 2248 | 7-21 | 33°-51' | 126°-38' | FIVE SUGAR DOGS | 6 miles | 6 kts 000°(T) | Lookout | Destroyed two by gunfire. |

- 22 -

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U.S.S. THREADFIN (SS 410)

CONFIDENTIAL

Subject: U.S.S. THREADFIN - Report of War Patrol No. THREE.

— page 132 —
U.S.S. THREADFIN (SS 410)

CONFIDENTIAL

Subject: U.S.S. THREADFIN - Report of War Patrol No. THREE.

— page 133 —
U.S.S. THREADFIN (SS 410)

CONFIDENTIAL
Subject: U.S.S. THREADFIN - Report of War Patrol No. THREE.
(H) ATTACK DATA (Cont'd.)

GUN ATTACK REPORT FORM

U.S.S. THREADFIN (SS 410) Gun Attack No. ONE Patrol No. THREE.
Time: 1432 (I) Date: 7-14-45. Latitude: 38°-37' N. Longitude: 120°-54' E.

TARGET DATA - DAMAGE INFLICTED

Sunk: One three-masted wooden cargo schooner. 150 tons. Length - 90
feet. (estimated) Schooner was carrying coal.

Damage Deter- Target was seen to sink after about fourteen 5" hits and about
mined By: twenty 40mm hits.

DETAILS OF ACTION

5"/25, 40mm, and 20mm guns were used. A total of 21 rds. 5"/25 H.C. with
Mk. 29-3 fuses, 38 rds. 40mm H.E.I.T., and 118 rds. 20mm was fired. Opening
range was 1300 yards, target was closed to 600 yards. High periscope was used
for spotting, using the TDC for hitting gun range keeper and utilizing radar for
spotting. Local control was used on the 40mm and 20mm guns. Target sank by
flooding; no fires were started.

U.S.S. THREADFIN (SS 410) Gun Attack No. TWO. Patrol No. THREE.
Time: 1309 (I) Date: 7-15-45. Latitude: 39°-30.5' N. Longitude: 123°-41.5' E.

TARGET DATA - DAMAGE INFLICTED

Sunk: One four-masted wooden cargo schooner. 300 tons. Length 130 ft.
(Obtained by radar range and periscope.)

Damage Deter- Target capsized after thirteen 5" hits and twenty to twenty-five
mined By: 40mm hits.

DETAILS OF ACTION

5"/25 and 40mm guns were used. A total of 16 rds. of 5"/25 H.C. with Mark
39-3 fuses and 40 rds. of 40mm H.E.I.T. was fired. Opening range was 1200 yards,
closed to 350 yards. Fire control used was same as in Attack No. ONE.

- 29 -

— page 134 —
U.S.S. THREADFIN (SS 410)

CONFIDENTIAL

Subject: U.S.S. THREADFIN - Report of War Patrol No. THREE.