The Korean War Chronology

PHASE 1: 27 June-15 September 1950
(UN Defensive)

UN Defensive 1950 Campaign Streamer
25 June North Korean forces cross border with South Korea. North Korean People's Army (NKPA) numbers approximately 135,000 men; Republic of Korea (ROK) Army contains 98,000 soldiers.
28 June NKPA forces capture Seoul.
1 July First U.S. ground combat troops, Task Force Smith (1st Battalion, 21st Infantry, 24th Infantry Division), arrive in Korea.
3 July Inchon falls to the NKPA.
5 July Task Force Smith engages and delays advancing NKPA forces at Osan in first U.S. ground action of the war.
8-12 July 21st Infantry stalls NKPA advances at Chochiwon.
10-18 July 25th Infantry and 1st Cavalry Divisions begin movement to Korea from Japan; 29th Regimental Combat Team sails from Okinawa for Korea; 2d Infantry Division prepares to embark from Seattle.
13-16 July 19th and 34th Infantry Regiments, 24th Infantry Division, fight delaying actions at Kum River line.
19 July 24th Infantry Division begins defense of Taejon.
20 July Taejon is captured by NKPA; 24th Infantry, 25th Infantry Division, captures Yechon.
25 July 29th Regiment engages the enemy near Chinju.
31 July 5th Regimental Combat Team arrives in Korea from Hawaii.
4 August Naktong (Pusan) Perimeter is set up.
8-18 August NKPA attempts to penetrate Naktong (Pusan) Perimeter and is repelled by 24th, 2d, and 25th Infantry Divisions along with Marine elements in the First Battle of the Naktong Bulge.
15-20 August Elements of 23d and 27th Infantry Regiments and ROK 1st Division successfully defend Naktong (Pusan) Perimeter in the Battle of the Bowling Alley (west of Taegu).
31 August-19 September Second Battle of the Naktong Bulge.

PHASE 2: 16 September-2 November 1950

UN Offensive 1950 Streamer
15 September U.S. X Corps, with the 1st Marine Division, in the lead, conducts amphibious landing at Inchon.
16 September U.S. Eighth Army begins its offensive northward out of the Pusan Perimeter.
20 September 1st Marine Division drives northeast across Han River.
26 September X Corps' 31st Infantry Regiment, 7th Infantry Division, moving east from Inchon, links up with Eighth Army's 7th Cavalry Regiment, 1st Cavalry Division, south of Suwon.
27 September U.S. and Republic of Korea (ROK) forces capture Seoul, the South Korean capital.
1 October ROK I Corps crosses 38th Parallel and then advances up the east coast.
6-7 October Two ROK II Corps divisions cross 38th Parallel in central Korea.
9 October U.S. Eighth Army forces cross 38th Parallel north of Kaesong and attack northward toward P'yongyang, the North Korean capital.
10 October ROK I Corps captures the major port of Wonsan.
14-17 October 7th Infantry Division loads on ships at Pusan in preparation for amphibious landings by X Corps along the northeastern coast above the 38th Parallel.
19 October 1st ROK Division and U.S. 1st Cavalry Division capture P'yongyang.
25 October Communist Chinese Forces (CCF) offensive operations begin north of Unsan with fighting between CCF and ROK forces; first Chinese soldier is captured.
26 October 1st Marine Division, X Corps, lands at Wonsan. ROK forces reach the Yalu River at Chosan.
29 October U.S. 7th Division lands at Iwon.
1-2 November First U.S. battle with CCF, near Unsan.

Phase 3: 3 November 1950-24 January 1951

CCF Intervention, 1950-51 Streamer
3-6 November Communist Chinese Forces (CCF) offensive continues in Eighth Army and X Corps zones.
11 November X Corps resumes advance north.
24 November Eighth Army moves north from the Chongchon River.
25 November Chinese forces attack Eighth Army center and right.
27 November X Corps attacks from west in support of Eighth Army; Chinese forces strike X Corps at Chosin Reservoir.
29 November Eighth Army begins general withdrawal from Chongchon River line to defensive line at P'yongyang.
29 November-1 December Chinese forces devastate U.S. 2d Infantry Division as it guards Eighth Army withdrawal.
30 November X Corps starts retreat to port of Hungnam.
5 December Eighth Army falls back from P'yongyang.
11-24 December X Corps loads on ships for evacuation to Pusan; General Almond sails on Christmas Eve.
23 December General Walker is killed in auto accident north of Seoul.
26 December Lt. Gen. Matthew B. Ridgway arrives in Korea as Eighth Army commander.
31 December-5 January New CCF offensive begins.
4 January Seoul falls; Eighth Army pulls back to line forty miles south of Seoul.
5 January Port of Inchon is abandoned.
7-15 January Enemy offensive subsides; UNC situation stabilizes intelligence sources report many enemy units had withdrawn to refit.
15 January Army Chief of Staff General J. Lawton Collins, on a visit to Korea, declares that "we are going to stay and fight."

PHASE 4: 24 January-21 April 1951
(First UN Counteroffensive)
22 April-July 1951 (CCF Spring Offensive)

First UN Counteroffensive streamer CCF Spring Offensive 1951 streamer
25 January Eighth Army counterattacks in Operation THUNDERBOLT, which starts in the west and gradually expands eastward.
10 February In the west, Inch'on is recaptured, as I Corps approaches the Han River
11-12 February Chinese forces attack X Corps, forcing advancing ROK units to fall back toward Wonju.
13-15 February Battle of Chipyong-ni.
18 February Reports confirm an enemy withdrawal along the entire central front.
21 February Eighth Army launches Operation KILLER, a general advance north by IX and X Corps
28 February Enemy resistance south of the Han River collapses.
7 March General Ridgeway begins Operation RIPPER; the objective is Line Idaho, just south of the 38th Parallel.
14-15 March UN troops enter Seoul, the South Korean capital.
31 March Eighth Army is positioned along the Idaho line.
2-5 April General Ridgeway puts Operation RUGGED into motion; the objective is Line Kansas, some ten miles above the 38th Parallel.
9 April The I and IX Corps and the ROK I Corps reach the Kansas line; the two U.S. corps continue to advance farther north.
11 April General MacArthur is relieved as UNC commander; General Ridgeway succeeds him.
14 April General Van Fleet assumes command of Eighth Army.
22 April The expected Chinese and North Korean spring offensive begins, with the strongest attacks in the west, toward Seoul.
30 April The enemy offensive is stopped just north of Seoul.
15-20 May The Chinese and North Koreans resume the offensive, focusing on the east-central region; General Van Fleet begins a counterattack.
31 May The Eighth Army advances nearly to Line Kansas.
1 June General Van Fleet strengthens the Kansas line and sends forces farther north, toward Line Wyoming.
23 June The Soviet Union calls for armistice talks.

PHASE 5: 9 July 1951-27 July 1953 (UN Summer-Fall Offensive 1951)
(Second Korean Winter) (Korea, Summer- Fall 1952)
(Third Korean Winter) (Korea, Summer 1953)

UN Summer-Fall Offensive 1951 Campaign Streamer Second Korean Winter 1951-1952 Korea Summer-Fall 1952 Campaign Streamer Third Korean Winter 1952-1953 Campaign Streamer Korea Summer 1953 Campaign Streamer
10 July 1951 Armistice talks begin at Kaesong.
23 August Communist side breaks off negotiations.
5 September North Koreans abandon Bloody Ridge, after UN forces, led by U.S. 2d Infantry Division's 9th Infantry, outflank it.
12 September-13 October 2d Infantry Division, using the 72d Tank Battalion to tactical advantage, seizes Heartbreak Ridge.
3-19 October Five UN divisions advance to Line Jamestown, some four miles beyond the Wyoming line, to protect the Seoul-Chorwon railway.
25 October Armistice talks resume, now at Panmunjom.
12 November General Ridgway, the UNC commander, instructs General Van Fleet to cease Eighth Army offensive operations and to assume an "active defense."
12 May 1952 General Mark W. Clark assumes command of the UNC.
8 October UN delegation calls an indefinite recess to armistice talks, reflecting a long lack of any progress.
11 February 1953 Lt. Gen. Maxwell D. Taylor takes command of the Eighth Army.
26 April Armistice talks begin again.
6-11 July General Taylor abandons Pork Chop Hill, a 7th Infantry Division outpost, to the Chinese as not worth further fighting.
13-20 July Chinese launch a six-division attack against ROK II Corps and U.S. IX Corps south of Kumsong; after falling back some eight miles to below the Kumsong River, UN forces regain the high ground along the river.
27 July Armistice agreement is signed at 1000; all fighting stops twelve hours later; both sides have three days to withdraw two kilometers from the cease-fire line.

Posters Available as PDF Files:

Phase 1, 27 June-15 September 1950

  • (UN Defensive)

Phase 2, 16 September-2 November 1950

  • (UN Offensive)

Phase 3, 3 November 1950-24 January 1951

  • (CCF Intervention) Offensive)

Phase 4, 25 January-21 April 1951 22 April-8 July 1951

  • (First UN Counteroffensive) (CCF Spring Offensive)

Phase 5, 9 July 1951-27 July 1953 (Last Offensive)

  • (UN Summer-Fall Offensive 1951)
  • (Second Korean Winter)
  • (Korea, Summer- Fall 1952)
  • (Third Korean Winter)
  • (Korea, Summer 1953)