Operation Yo-Yo: Transportation during the first year of the Korean War
October 9, 2013
In June 1950, the North Korean government decided to unify the Korean Peninsula under a single communist rule by crossing the 38th parallel and conquering its neighbor to the south, the Republic of Korea (ROK). The North Korean army had just returned from combat in China, where the communists under Mao Tse Tung had defeated the nationalists under Chiang Kai Shek. The inexperienced ROK Army fell back in ruin.
Consequently, President Harry Truman decided to reinforce the ROK Army and reestablish the 38th parallel. Like all wars, transportation and lines of communication significantly affected combat during the first year. Because the U.S. lines of communication expanded and contracted from Pusan to the Chinese border and back, the men unofficially called the fighting that first year "Operation Yo-Yo."
PORT OPERATIONS AT PUSAN
The first objective of the U.S. intervention in the Korean War was to stabilize a perimeter around Pusan, the only deep draft port available to the U.S. Army. Pusan provided the critical link in the lifeline of men and materiel from Japan and the United States.
The bulk of supplies arrived by World War II Liberty and Victory ships from the Military Sea Transportation Service. Task Force Smith, built around the 1st Battalion, 21st Infantry Regiment, 24th Infantry Division, arrived in Korea on July 1, 1950, to buy time for the arrival of the rest of the 24th Infantry Division from Japan. With a small combat footprint, stevedores arrived to open up the port.
The 8057th Provisional Port Company, which arrived on July 2, began operations immediately, discharging 309,000 tons of cargo during July. The Far East Command quickly established the Pusan Base Command on July 4 to supervise port operations. Task Force Smith moved forward by rail and truck to fight the first U.S. engagement with the North Koreans at Osan on July 5.
With initial port operations established, a truck platoon arrived on July 8, and the 9th Army Unit Transportation Railway Service (Provisional) arrived the next day. The 25th Infantry Division began arriving on July 9, and the 1st Cavalry Division arrived next.
RAIL LINES OF COMMUNICATION
Fortunately, Korea had a well-developed rail infrastructure, thanks to the Japanese, that could move the troops forward. The 8059th Army Unit supervised railroad operations and maintenance, but the Korean National Railroad provided the crews for the locomotives. As more logistics units arrived, the Pusan Base Command was reorganized into the Pusan Logistical Command under Brig. Gen. Paul F. Yount on July 13.
With three Army divisions and a Marine brigade in place, the Eighth Army increased its logistics footprint. The 70th Transportation Truck Battalion arrived with four truck companies from its base in Yokohama, Japan, on July 14 to conduct port clearance. On July 18, the 709th Transportation Railway Grand Division arrived in Korea to control the operations of the Korean National Railroad by establishing communications offices at various locations along the railways.
Elements of the 2nd Transportation Medium Port, also from Yokohama, arrived on July 23, and the 69th Transportation Truck Battalion arrived at Pusan on Aug. 7 to support I Corps, which had reactivated on Aug. 2. The lead regiment of the 2nd Infantry Division arrived from Fort Lewis, Wash., in early August. Through the month of August, I Corps held the Pusan perimeter against repeated enemy attacks while transportation operations expanded.
Rail was the prime mover during this phase, since roads through the mountains were few and generally in poor condition. On Aug. 26, the 8059th Army Unit and 709th Transportation Railway Grand Division were inactivated and their assets were transferred to the Transportation Section Rail Division to create the 3rd Transportation Military Railway Service (TMRS) at Pusan.
That same month, the 764th and 765th Transportation Railway Shop Battalions and the 714th Transportation Railway Operating Battalion (TROB) arrived in Korea, but they were understrength and only about 20 percent of their personnel had any railroad experience. So the railroad men rode the trains mostly to make sure the Koreans stayed on schedule.
On Aug. 31, the 7th Transportation Major Port assumed control of Pusan from the 2nd Medium Port and discharged over a million tons of materiel a month, but the limited capacity of the port left ships at anchorage for weeks. The Pusan Logistical Command was reorganized into the 2nd Logistical Command in September to receive, store, and push supplies forward to the Eighth Army.
PORT OPERATIONS AT INCHON
With the port and port clearance capability firmly established, the American's short lines of communication became its strength as compared to the long, vulnerable enemy lines of communication stretching back to its bases in North Korea. To break out from Pusan, Gen. Douglas McArthur ordered X Corps in Japan to conduct an amphibious landing at Inchon on Sept. 15. This would both open up another port and threaten the North Korean Army's supply line.
The day after the 1st Marine Division landed, the 55th Transportation Truck Battalion also landed at Inchon in the early hours of Sept. 16. After two days on the beach, the battalion proceeded to Kimpo Airfield, where it unloaded cargo planes and relayed the supplies to the front in support of IX Corps, which later assumed command of the 2nd and 25th Infantry Divisions on Sept. 23. The 2nd Engineer Special Brigade brought the 7th Infantry Division ashore behind the 1st Marine Division at Inchon on Sept. 18. To operate the port of Inchon, the 3rd Logistical Command was activated on Sept. 19.
The threat worked, and the communists beat a hasty retreat. In their retreat from the ROK, the North Koreans demolished railroads and bridges. The 3rd TMRS had moved earlier to Taegu and had organized two rail reconnaissance groups for advance service. The 3rd TMRS and Korean National Railroad then repaired the tracks and bridges behind the advance of the Eighth Army.
ADVANCING INTO NORTH KOREA
On Oct. 7, the Eighth Army crossed the 38th parallel, but the advance through North Korea was hampered by badly damaged roads. The 714th TROB meanwhile established rail transportation offices from Pusan to Taegu, and on Oct. 12 it assumed operational control of all Korean rail activities from Taegu south to the coast. The 3rd TMRS moved up to Seoul on Oct. 18. The 714th TROB then moved to Sindong and began operating as a rail traffic regulating organization rather than as a railway operating unit.
By Oct. 19, Eighth Army units occupied Pyongyang, the North Korean capital. The 69th Transportation Truck Battalion advanced to Pyongyang in November to support I Corps. The 55th Transportation Truck Battalion supported IX Corps, the 52nd Transportation Truck Battalion supported X Corps, and the 70th Transportation Truck Battalion conducted port clearance. With the Eighth Army just short of the Chinese border, victory seemed at hand.
Because of his success with the landing at Inchon, McArthur pulled X Corps out of fighting in Seoul on Oct. 1 and deployed it to the east side of the peninsula. X Corps landed at Wonsan on Oct. 26, at Iwon on Oct. 26, and then opened up Hamhung as the main port of debarkation. X Corps then pushed to the Chinese border while I and IX Corps did likewise. The 52nd Transportation Truck Battalion then arrived at Hamhung in support of X Corps.
On Nov. 29, the Chinese army poured across the border to cut off U.S. forces and destroy them in their retreat. The 55th Transportation Truck Battalion was involved in relaying cargo to the front when the Chinese attacked, and its trucks then evacuated the 2nd Infantry Division through a gauntlet of Chinese ambushes. It took the trucks of the 55th Battalion several trips to bring the 2nd Infantry Division back.
Col. Paul Freeman commanded the 28th Regimental Combat Team at Chip'yong-ni. It had fought the rear guard action to protect the retreat of the 2nd Infantry Division. Forced back from every position the U.S. Army had tried to defend, Freeman knew his men could hold this circle of hills.
While the Chinese and North Koreans mastered the method of infiltrating their enemy's rear, Freeman knew that the Chinese Army was farther from its supply base than his regiment was from its own. He was right. Tanks reopened his lines of communication and the Indianhead division fell back no further.
As the Chinese poured around the Chosin Reservoir on the east side of the peninsula, the 1st Marine Division absorbed what remained of the battered 7th Infantry Division and fought its way through 10 miles of roadblocks to Koto-ri.
There, Lt. Col. John U. D. Page, an artillery officer from the X Corps staff attached to the 52nd Transportation Truck Battalion, established a traffic control point for the Marines and Soldiers on the supply route. Page became actively involved in the defense of Koto-ri.
On Dec. 5, Marine Corps Maj. Gen. Oliver P. Smith ordered the withdrawal from Koto-ri. The 52nd Transportation Truck Battalion, having dropped from 3rd Infantry Division's Task Force Dog at Chinghung-ni on Dec. 7, met up with the Marines at Koto-ri the next day. On Dec. 9, the Marines loaded up on the Army trucks for their arduous journey south. After reaching the port, X Corps withdrew from Hamhung to Pusan from Dec. 11 through Dec. 24.
Page joined the rear guard of the retreating column that came under frequent flank attack. Blocked at Sudong near the mouth of the pass on Dec. 10, Page led the counterattack and was killed. Page's heroic action earned him the Navy Cross, which was later upgraded to the Medal of Honor.
As Eighth Army fell back, so did the Transportation units. The 69th Transportation Truck Battalion likewise withdrew on Dec. 3, arriving at Pusan on Dec. 12. Its mission shifted to transporting ammunition and supplies. The 55th Transportation Truck Battalion also fell back as far south as Pusan. Eighth Army eventually fell back to near the 38th parallel, where the war had started.
The Chinese threat to Seoul subsequently forced the 3rd TMRS to relocate its headquarters back to Taegu on Dec. 18, and the railroad was used to transport as much materiel as possible south. On Jan. 1, 1951, the 714th TROB moved back to Pusan to run the rail operations of Taegu.
STABILIZING THE LINES OF COMMUNICATION
As the frontline settled into a stalemate, the 55th Battalion advanced north to stage from Taegu, Taejon, and Wonju. The 70th Transportation Truck Battalion conducted port clearance to the depot. From there, cargo ran north by rail, and the 52nd Battalion pushed cargo out of Wonju to the X Corps rear.
The 69th Transportation Truck Battalion was relieved by the Pennsylvania National Guard's 167th Transportation Battalion in early 1951 and moved to Taegu. The 351st Transportation Highway Transport Group arrived in Korea on March 5, 1951, and on March 11 moved to Taegu to assume control of all trucking operations in Korea. The 70th Transportation Truck Battalion then moved to Hongchon on June 5, 1951, to support X Corps. The lines of communication remained stable for the remainder of the war.
While good logistics may not ensure success in combat, the lack of it can guarantee defeat. Lines of communication dictate the routes by which armies supply themselves and consequently fight; so the closer a force is to its supply base, the shorter the turnaround in logistics. The Korean War illustrates how the length of the supply line affects operations.
The initial U.S. combat operations of the Korean War focused on defending the one major seaport left in South Korea's hands: Pusan. Once this base of supply was secured, MacArthur landed X Corps at Inchon to threaten the enemy's overextended supply line, forcing them back across the 38th parallel.
Following this success, X Corps seized the port of Hamhung and advanced near the Chinese border. With the logistics situation reversed, the Chinese intervened and infiltrated to cut the overextended U.S. supply lines, forcing I and IX Corps back to the 38th parallel. Similarly, the overwhelmed X Corps had to fall back to its supply base at Hamhung and was later ordered out. It joined the other two corps to form a new line of defense.
The war then settled into trench warfare similar to World War I for the next two years, with little advancement on either side. The Korean War ended 60 years ago in an armistice on July 27, 1953, but its lessons remain relevant today.
Richard E. Killblane is the command historian for the Transportation Corps. He has a bachelor's degree from the U.S. Military Academy and a master's degree in history from the University of San Diego. He has traveled to Southwest Asia five times to record the history of transportation operations during Operations Iraqi Freedom and Enduring Freedom and once to Haiti during Operation Unified Response. He has published numerous articles and books, including "The Filthy Thirteen," "War Paint: The Filthy Thirteen Jump Into Normandy," "Mentoring and Leading: The Career of Lieutenant General Edward Honor," and "Circle the Wagons."
This article was published in the October-December 2013 issue of Army Sustainment magazine.