The 2nd Marine Infantry Division (; Hanja: 第2海兵師團), also known as Blue Dragon Division (; Hanja: 青龍部隊), is an infantry division of the Republic of Korea Marine Corps.

History
On June 1, 1965, Prime Minister of South Vietnam Nguyễn Cao Kỳ requested military aid from South Korea. To support South Vietnam from communist North Vietnam, Korea State Council agreed to send a Division and its supporting units on July 2, and National Assembly of South Korea made final decision to send troops on August 13.

On August 17, the Republic of Korea Marine Corps attached various battalions, companies, and platoons to the 2nd Marine Regiment to increase its size to a brigade. The Marine Corps originally planned battalion to regiment size unit, but reports from Vietnam said that separating army and Marines was more appropriate to operate.

With President Park Chung-hee in attendance, the 2nd Marine Brigade was formally activated at the ROK Marine Corps training camp at Pohang on September 20, 1965.

The 2nd Marine Brigade was a mostly volunteer group that included many of South Korea's early Chaebols (Lee Kun-Hee, Ohn Jee-won, Chung Mong-koo), intellectuals and staunch anti-communists. Drafting only took place from November 4, 1967, following the heavy casualties of 
Operation Dragon Fire.

Vietnam War

The Blue Dragons were initially deployed to Cam Ranh Bay in September 1965, but in December moved to Tuy Hòa to provide security against the NVA 95th Regiment.

In August 1966, the Blue Dragons moved to Chu Lai and was placed under the operational control of the III Marine Amphibious Force (III MAF). Under an arrangement with the USMC, air assets would be provided to the brigade and assigned the same priority for available aircraft as American units. A team from Subunit One, 1st ANGLICO was dispatched and charged with the mission of keeping an air umbrella over the Blue Dragon Brigade in and out of the field. A two-man fire control team was assigned to each ROKMC infantry company at all times.

Initially, the AK-47-equipped Vietcong (VC) and People's Army of Vietnam (PAVN) had somewhat superior small-arms to South Korean soldiers, since they were armed with World War II-era weaponry (M1 Garand and M1 carbine), although ROK forces like others relied on overwhelming use of heavy artillery and air support against small-arms and mortar units. They later received more modern weapons from the United States military such as the M16 rifle.

Significant operations and actions involving the Brigade include:

 Operation Lightning in Khánh Hòa Province from 8 to 14 November 1965
 Operation Flying Tiger: in early January 1966, joint operation with U.S./Army of the Republic of Vietnam (ARVN) Forces.
 Operation Van Buren: a rice harvest security operation with the 101st Airborne Division and ARVN in Phú Yên Province from 19 January to 21 February 1966 results in US claims of 346 VC killed for the loss of 45 ROK and 55 U.S.
 Operation Longstreet, an engineering security operation in Bình Định and Phú Yên Provinces
 Operation Lee: with the ARVN 4th Regiment in Quảng Ngãi Province from 3 to 10 October 1966
 Battle of Tra Binh Dong: on 15 February 1967, 11th Company of the Blue Dragons was dug in near the village of Tra Binh Dong in Quảng Nam Province when they were attacked by an estimated three VC Battalions supported by heavy mortar and recoilless rifle fire. The VC launched secondary attacks on each flank of the company before attacking with one Battalion against the Company center, breaching the perimeter and using flamethrowers and bangalore torpedoes against the company's bunkers. The Company counterattacked and with the aid of a South Korean Marine quick reaction company helidropped into the position succeeded in driving back the VC with ROK forces claiming to have killed 243.
 Operation Giant Dragon: in Quảng Ngãi Province from 17 to 22 February results in ROK claims of 16 VC killed and 61 weapons captured
 Operation Dragon Fire: in Quảng Ngãi Province from 5 September to 30 October 1967 claims that 541 VC were killed.
 The recapture of Hội An: during the Tet Offensive
 Operation Daring Rebel: a search and destroy operation with the ARVN 2nd Division and American forces on Barrier Island 24 km south of Danang, Bình Định Province from 5 to 20 May 1969 results in claims of 4 VC killed
Operation Victory Dragon: on Go Noi Island, Quảng Nam Province from October 1968 to December 1970.
Operation Pipestone Canyon: on Go Noi Island, Quảng Nam Province from 26 May to 7 November 1969.
 Operation Defiant Stand: an amphibious assault with the 1st Battalion, 26th Marines on 7 September 1969. This was the first amphibious assault ever conducted by the Republic of Korea Marine Corps
 Operation Hoang Dieu 101: with III MAF and the ARVN 51st Regiment in Quảng Nam Province from 17 December 1970 to 19 January 1971, unknown casualties
 Operation Golden Dragon II: a clear and search operation in Quảng Nam Province from 4 to 21 January 1971
 Operation Hoang Dieu 103: with III MAF and the ARVN 51st Regiment in Quảng Nam Province from 3 February to 10 March 1971

The conduct of ROK forces is praised by some South Korean participation in Vietnam states that "the Koreans were thorough in their planning and deliberate in their execution of a plan. They usually surrounded an area by stealth and quick movement. While the count of enemy killed was probably no greater proportionately than that of similar American combat units, the thoroughness with which the Koreans searched any area they fought in was attested to by the fact that the Koreans usually came out with a much higher weaponry count than American forces engaged in similar actions."

A total of 320,000 South Koreans served in the Vietnam War, with a peak strength (of any given time) at around 48,000. About 4,000 were killed.

Commanders during Vietnam War
Sep 1965-1967 : Brig. Gen. Kim Yun-sang 
Oct 1967 : Brig. Gen. Yi Bong-chool 
1970 : Brig. Gen. Lee Dong-yong

Order of battle during Vietnam War
2nd Marine Brigade 
 Direct Control Company
1st Marine Battalion
2nd Marine Battalion
3rd Marine Battalion
5th Marine Battalion
2nd Field Artillery Battalion
628th Field Artillery A Unit (Army)

Unit statistics for the Vietnam War

War crimes
In February 1968, soldiers of the Brigade were accused of perpetrating the Phong Nhị and Phong Nhất massacre. 

In February 2023, The Seoul court awarded Nguyen Thi Thanh compensation of $24,000, with the judge finding that Nguyen's relatives were killed on the spot and the plaintiff seriously wounded, and that this is obviously illegal.

After the Vietnam War
After returning from the Vietnam War, the 2nd Marine Brigade was expanded and restructured into as the 2nd Marine Division in 1981.

See also

 Republic of Korea Marine Corps
 1st Marine Division
 Vietnam War
 Capital Mechanized Infantry Division
 9th Infantry Division
 Republic of Korea Armed Forces
Ganghwa Island shooting

References

1965 establishments in South Korea
Republic of Korea Marine Corps
Marine
Military units and formations established in 1965