23rd Infantry Division ( United States ) The 23rd Infantry Division , more commonly known as the Americal Division , of the United States Army was activated 27 May 1942 on the island of New Caledonia . In the immediate emergency following Pearl Harbor , the United States had hurriedly sent three individual regiments to defend New Caledonia against a feared Japanese attack . This division was the only division formed outside of United States territory during World War II ( a distinction it would repeat when reformed during the Vietnam War ) . At the suggestion of a subordinate , the division ' s commander , Major General Alexander Patch , requested that the new unit be known as the " Americal Division " — the name being a contraction of " American , New Caledonian Division " . This was unusual , as most U . S . divisions are known by a number . After World War II the Americal Division was officially re - designated as the 23rd Infantry Division . However , it was rarely referred to as such , even on official orders . During the Vietnam War the division had a mixed record . It combined solid service in numerous battles and campaigns with the My Lai massacre , which was committed by a platoon of the division ' s subordinate 11th Infantry Brigade , led by Lieutenant William Calley . The division was inactivated following its withdrawal from Vietnam in November 1971 . Operations in World War II . The 164th Infantry Regiment of the Americal Division went into action on Guadalcanal on 13 October 1942 alongside the 1st Marine Division as the first United States Army unit to conduct an offensive operation against the enemy in either the Pacific or European Theater of Operations . ( Eight other U . S . Army divisions began offensive combat operations in late 1942 : the 32nd and the 41st Infantry Divisions in the Pacific on New Guinea ; and in North Africa , the 1st , 3rd , 9th , and 34th Infantry Divisions , and the 1st and 2nd Armored Divisions . ) Formation . As the " square " divisions of the Army National Guard were being transitioned to the triangular division TO & E in 1942 , they each " shed " an infantry regiment , leaving several trained and operational " orphan " regiments available for independent service . New Caledonia , a likely target for the Japanese for its critical strategic position on the lines of communication with New Zealand and Australia and it nickel and chrome mines , was now under the control of the Free French with a poorly equipped and trained native force and a company of Australian commandos . The United States Army was already building airfields with Australian labor on the island which according to early agreements fell into the British sector and delegated to the Australians for defense . The French objected to the arrangement and , increasingly worried about Japanese invasion , demanded American forces . With pressing needs building up defenses in Hawaii and Australia Army planners decided to put together a force rather than commit an already organized division . The regiments available through the reorganization of divisions along with other elements made available a force of about 15 , 000 men . This force , designated Task Force 6184 and often mentioned as Poppy Force ( New Caledonia was code named Poppy ) , under Brig . Gen . Alexander M . Patch , Jr . had the elements of a division and more in its composition . For example there was a brigade headquarters from the 26th Division , two infantry regiments and a field artillery regiment along with support elements augmented by a battalion of light tanks , antiaircraft and coast artillery regiments and a pursuit squadron . The force ' s mission was to hold New Caledonia and was independent , directly under the War Department in Washington . Within two weeks , despite an urgent need of shipping elsewhere and at the cost of delaying and rearranging schedules elsewhere and consultations at the head of state level , Task Force 6184 along with some 4 , 000 troops destined for Australia were assembled in the largest single troop convoy , Designated BT - 200 and totaling over 20 , 000 troops aboard seven transports , up until that time . The convoy sailed from New York on 23 January 1942 and reached Melbourne on 26 February . This large and critical convoy was covered by a striking group and long range air between its intended position and Japanese forces arranged by Admiral King ( COMINCH ) with Admiral Nimitz ( CINCPAC ) . Despite some desire locally to use the force to reinforce Australia or the Netherlands East Indies , under direct orders from Washington the force move secretly not even informing the French to New Caledonia . Transshipment of troops and equipment was completed in Melbourne and the seven transports departed on 7 March ( Australian time ) for New Caledonia as convoy ZK - 7 , arriving six days later . General Patch , preceding the force by air , had arrived on 5 March with news for the French that American forces were underway . Despite having no early prospect of reinforcements another infantry regiment arrived in April along with the authority to organize an infantry division from elements of the overall force and in May the Americal Division was organized . The " line " regiments selected were the 132nd Infantry Regiment , formerly part of the 33rd Infantry Division of the Illinois National Guard , the 164th Infantry Regiment from North Dakota , and the 182nd Infantry Regiment from Massachusetts . Guadalcanal . In contrast to several other US Army divisions in the Pacific War , soldiers in the Americal division received extensive weapons training as well as company - and battalion - level exercises in jungle terrain while at New Caledonia . Under the command of General Patch , the Americal Division was the first US Army unit to be sent to Guadalcanal . Largely because of transport constraints , the Americal arrived piecemeal , and was fed into combat alongside the battle - hardened and exhausted US 1st Marine Division , which it eventually relieved . Its soldiers were quick to assimilate from the Marines on Guadalcanal lessons on battle tactics against Japanese forces . Americal casualties were consequently less than what might be expected . Elements of the Americal Division defended Henderson Field against heavy enemy attacks on 23 – 25 October 1942 , and the following month took part in the offensive across the Matanikau River . In January 1943 , the 132nd Infantry Regiment of the division took Hill 27 and 31 of the Mount Austen complex . The division later participated in offensives to sweep Guadalcanal of remaining Japanese resistance . After the last Japanese defenders were killed , captured , or evacuated from the island , the division was relieved on 9 February 1943 . Despite its ad - hoc formation , the Americal Division fought well at Guadalcanal . The 164th Regiment took part in repulsing a major Japanese offensive in October 1942 , while the 132nd Regiment assaulted the highly fortified Japanese Gifu defensive complex at Mount Austen in January 1943 . Historians describe the Americal Division as the most effective of all the US Army divisions in that conflict . Following the withdrawal of the 1st Marine Division , the division continued operations on Guadalcanal as part of the U . S . XIV Corps until all of the Japanese resistance had ended . Bougainville . The division next moved to the Fiji Islands , beginning 5 March 1943 , to assume the defense of the main island of Viti Levu and to engage in extensive training . During the period 25 December 1943 to 12 January 1944 the Americal Division landed on Bougainville , relieving the 3rd Marine Division . They were given the task ( alongside the 37th Infantry Division and a Marine defense battalion ) of holding and extending the right half of a previously established perimeter . Warned by intelligence , they met a massive and sustained Japanese counter - attack , which began on 7 March 1944 . Despite ample warning and thorough defensive preparations , the battle soon degenerated into a bitter , close - quarters infantry affair , with artillery restricted by the need to avoid friendly troops and tanks unable to reach the scene . The 37th and Americal Divisions stood firm , and by 25 March , the Japanese were forced to retreat . It was the last Japanese ground offensive in the South Pacific . The division went on the offensive in March 1944 , driving the Japanese east of Mavavia River , 7 – 9 April 1944 , and seizing numerous strategic hill bases during the remainder of the month . Training and long - range patrol activity continued until 30 November 1944 when the division was relieved . Philippines . On 8 January 1945 , the division began movement to Leyte and Samar , to take part in cleaning out remaining Japanese forces on those islands , and to invade Biri , Capul , Ticao , and Burias . On Leyte , the division was relieved on 13 March 1945 and then landed on Cebu on 26 March , and seized the city and airfield by 28 March . Divisional combat teams made landings on Bohol , Negros , and Mindanao , where they cleared out pockets of resisting Japanese until 17 June when ordered to return to Cebu , arriving on 25 June . Training continued on Cebu for the proposed invasion of Japan , but the Japanese surrendered on 14 August 1945 . On 10 September 1945 , the Americal Division landed in Japan and took part in the occupation of the Yokohama - Kawasaki - Yokosuka area . Postwar . The division returned to the United States on 21 November 1945 , and was inactivated on 12 December 1945 . It was reactivated on 1 December 1954 as the 23rd Infantry Division , retaining the name " Americal " as part of its official designation . On 2 December 1954 the 65th Infantry Regiment was assigned to the division . The 23rd Division encompassed geographically - separated units in the Caribbean region . On 10 April 1956 , the 65th Infantry Regiment was inactivated at Camp Losey , Puerto Rico , and relieved from assignment to the 23d , which itself was inactivated . The division served in the Panama Canal Zone until 10 April 1956 , when it was again deactivated . Vietnam . The Americal was reactivated 25 September 1967 in Vietnam from a combination of units already in Vietnam and newly arrived units . Its precursor , a division - sized task force known as Task Force Oregon was created in Quang Ngai and Quang Tin provinces from the 3rd Brigade of the 25th Infantry Division , the 1st Brigade of the 101st Airborne Division , and the 196th Light Infantry Brigade ( all separate brigades that deployed to Vietnam in 1966 ) . Task Force Oregon operated in close cooperation with the 1st Marine Division in the I Corps Military Region . As more US Army units arrived in Vietnam the two divisional brigades were released back to their parent organizations and two arriving separate brigades were assigned to Task Force Oregon , which was in turn re - designated the 23rd Infantry Division ( Americal ) . The division was composed of the 11th , 196th , and 198th Light Infantry Brigades and divisional support units . Both the 11th and 198th brigades were newly formed units . The Americal , in Vietnam , suffered an important defeat at the Battle of Kham Duc but gave a solid performance during TET , The Battle of LoGiang and the Battle of Nui Hoac Ridge ( Hill 352 ) . Platoon Sergeant Finnis McCleery was awarded the Medal of Honor for his valiant efforts on Hill 352 . Sgt . Alan Allen was awarded the Silver Star for this same battle . Both men were members of A Co . 1 / 6 198th . 20 men from A Company were lost in the Battle of LoGiang on 8 February 1968 . A Co . of the 198th was awarded the Presidential Unit Citation for its heroic efforts in the Battle of LoGiang , 8 February 1968 . The Americal Division became notorious after a platoon of troops from the division led by Lieutenant William Calley slaughtered hundreds of South Vietnamese civilians in the My Lai massacre in March 1968 . A helicopter crew from the division ' s 123rd Aviation Battalion , led by Hugh Thompson , Jr . , attempted to intervene in the massacre and were later awarded the Soldier ' s Medal . Seymour Hersh broke the story of the massacre in November 1969 , and a year later 14 officers - including Samuel W . Koster , the division ' s commanding officer - were charged with covering the massacre up . Most of the charges were later dropped , but Koster was subsequently demoted and stripped of his Distinguished Service Medal . The 198th and 11th Brigades were withdrawn from Vietnam in November 1971 , and the division was inactivated . The 196th Brigade was reconstituted as a separate brigade and remained in Vietnam until 29 June 1972 , the last major combat unit to be withdrawn . Its 3rd Battalion , 21st infantry ( Gimlets ) was the last U . S . maneuver battalion to leave Vietnam , on 23 August 1972 . Insignia . The shoulder sleeve insignia was originally approved for the Americal Division on 20 December 1943 . It was redesignated for the 23d Infantry Division on 4 November 1954 . On 14 December 1967 the distinctive unit insignia was approved . The shoulder sleeve insignia ' s four white stars on a blue field are symbolic of the Southern Cross under which the organization has served . The blue color stands for infantry . On the distinctive unit insignia , the blue saltire ( cross of St . Andrew ) alludes to New Caledonia in the Southwest Pacific where the division was created and first activated on 27 May 1942 . Each of the four white stars stands for the Southern Cross constellation on its division insignia , as well as the four World War II campaigns ( Guadalcanal , Northern Solomons , Leyte and Southern Philippines ) in which the division participated . The anchor refers to the Presidential Unit Citation ( Navy ) awarded the division for Guadalcanal . The red arrowhead and Philippine sun stand for the assault landing , Southern Philippines , and the award of the Philippine Presidential Unit Citation ( 7 October 1944 to 4 July 1945 ) . The unsheathed sword with point to top refers to Vietnam where the division was active . In view of the division ' s origin and outstanding service in World War II and inasmuch as it was one of the few U . S . Army divisions to bear a name instead of a number , the division ' s former name " Americal " has been taken as a motto , the association with that name being both inspirational and of historical military significance .