History of CBMU 1 / 101 and CBD 1802 & CBD 1804


CBMU 1/101 - Korean War Seabees

Seabees During the Korean Conflict

                    1950 - 1953

by Larry  G. DeVries

Capt. CEC, USNR (Ret.)

(with contributions by Seabees who were there.)

Korean Seabees

The story of the Navy Seabees and their performance during the Korean Conflict begins in the immediate post World War II years. As with all of the U. S. armed services the Seabees were part of the release of active personnel during the 1945 to 1947 period. The World War was ended and over 12 million uniformed personnel were released from active duty beginning in 1945. (Source: History, Quick Study Guide, Bar Charts, Inc.).
There were several events during the post-war period that drew attention to possible future U. S. military actions. The period was one of developing world tension. The Soviet Union took over Hungary in 1947 and Czechoslovakia in 1948. The East Germans and the Soviets blocked the land access to the Allied sections of Berlin causing the Berlin Airlift during 1948-1949. The U. S. armed forces, including reserve forces, were engaged in the Berlin Airlift. The explosion of an atomic bomb by the Soviet Union in 1949 continued the escalation of tensions. (Source: History, Quick Study Guide).

The Seabees on active duty dropped from over 250,000 during World War II to a level of 3,300 active duty Seabees in 1949. That number increased to 6,000 by 1950 primarily due to increasing demand for construction and maintenance support at naval bases and stations worldwide. In general, the post-war period was a time of smaller operations and austere budgets for the Navy and the Marine Corps. (Source: Naval Historical Center, web site, http://www.history.navy.mil)

On June 25, 1950, the North Koreans crossed the 38th parallel and entered South Korea. The U. S. forces were shocked initially and absorbed the attack while withdrawing to the south. The theater commander was General Douglas MacArthur, Supreme Commander, Allied Powers Japan.

The Naval Forces Far East Command, was under the command of Admiral C. Turner Joy, USN, since August 1949. He reported in Japan to General MacArthur, who was later designated, Commander in Chief, UN Command. The Far East Command, including the mission of logistics support, was located in Japan and its principle bases were at Yokohama, Guam and at Subic Bay in the Philippines. All were significant distances from any action in Korea. The operating fleet was the Seventh Fleet under VADM Arthur D. Struble, USN. (Source: Various)

President Truman, reacting to the need for personnel for Korean operations, called out the nation’s reserve and National Guard units on 19 July 1950. As an example of the speed of mobilization, the first Marine Corps Reserve units reached Camp Pendleton, California, on 31 July 1950. (“First To Fight”, V. Krulak, 1984). By September 1, 1950, call-ups had brought in about 256,000 men into the three services. (Source: “A General’s Life, Gen. O. Bradley, 1983, p. 546). There were about 120 Marine Reserve training units at the time many co-located with Naval Reserve Centers. ("Unexpected Journey" by Randy K. Mills and Roxanne Mills, 2000).

The Seabees supported the U. S. Marine Corps in Korea as they had done in World War II. This was especially true of airfield maintenance and construction. The transition from prop-driven planes to jet aircraft occurred during the Conflict. From an engineering viewpoint the Pierced Steel Planking, or Marston mat, used so successfully as main runways in World War II for piston-engine aircraft, did not stand up to the punishment put out by jet aircraft. That fact demanded new methods and materials in airfield runway construction and a six-inch blacktop layer was often used. Cold weather, approximately that of northern Maine, and hot weather, approximately that of Washington, D. C., contributed to the stress on the work and the Seabees. The shortage of native skilled labor and lack of local supply sources contributed to the challenges of construction. (Source: “History of United States Military Logistics, 1935-1985”, J. Peppers, Jr., LEF, 1988.).​ 


The Korean War can be divided by the Marine Corps Engagements into distinct periods. These are:

27 June – 2 November 1950 North Korean Aggression

13 September – 17 September 1950 Assault on Inchon-Seoul

3 November 1950 – 24 January 1951 Communist China Aggression

25 January – 21 April 1951 First U. N. Counter Offensive

22 April – 8 July 1951 Communist China Spring Offensive

9 July – 27 November 1951 U. N. Summer-Fall Offensive

28 November 1951 – 30 April 1952 Second Korean Winter

1 May – 30 November 1952 Korean Defense Summer-Fall, 1952

1 December 1952 – 30 April 1953 Third Korean Winter

1 May – 27 July 1953 Korean Summer-Fall, 1953

(Source: “Almanac of Naval Facts”, USNI, 1964, Marine Corps Highlights)

Active duty Seabee battalions were not deployed to Korea as complete Mobile Construction Battalion units. The active duty Seabees were called upon to provide smaller construction units. The active duty units (see Table 1, Navy Seabee Units in Korea) were:

NCB-104 was formed by reactivation of a World War II unit in 1947. It arrived at Camp McGill, Japan, at the outbreak of the Korean Conflict. It was shortly converted into ACB-1. Strength about __?__.

General MacArthur landed with the United Nations forces at Inchon, South Korea, on September 15, 1950 successfully and drove north. The Seabees of ACB-1 were attached to the Ist Marine Division and were part of the landing force under RADM James H. Doyle, USN, Commander, Amphibious Force at Inchon.

ACB-1, Amphibious Construction Battalion -1, was organized in 1950 from NCB-104. It served at Inchon, Wolmi-Do, Red and Blue Beaches, and Yo Island in the Bay of Wonsan. Strength about __?__. Assigned to the 1st Marine Division (Source: Fire and Ice, M. Varhola, p. 111). Part of Task Force 90, and Operation Chromite, U. S. Army X Corps, during the Inchon landing (September 1950) and was part of landing of The Wonsan Campaign (October 1950).

The ACB-1 Seabees were landed on 15 September 1950 as part of the landing force under ____?____ Task Force 90. Their effort was directed at providing the pontoon causeways necessary to unload LSTs.

In May 1952, the ACB-1 Seabees managed to build an emergency airstrip on the small island of Yo Do while under heavy enemy fire. They built the 2,400-foot airstrip in 16 days. During the work, they were forced to repair the new shell holes made daily by the enemy batteries across the bay. During the year it was used, it saved more than 60 fliers and at least $10 million in aircraft. (Source for this and (*): Mobilizer, May-June 1992, p. 13; The Korean War, B. Catchpole, 2000, p. 235).

Other than NCB-104 in Japan at the outbreak, later converted into ACB-1, which deployed with MacArthur during the Inchon landing, only smaller-than-battalion size units were deployed and those were Detachments.

During the Korean War, the U.N. Far East Air Force (FEAF) used some 15 air bases in Japan to support combat operations in Korea. In addition, the Air Force either improved or constructed some 55 airfields. These air bases were all numbered and some became better known by their number than by their name. The more important of these airfields included: (Source: http://www.korea50.mil; definitions)​ 

K-1 Pusan West
K-2 Taegu 

K-3 Pohang-dong 

K-5 Taejon 

K-6 Pyongtaek 

K-8 Kunsan

K-9 Pusan East 

K-10 Chinhae 

K-13 Suwon 

K-14 Kimpo
K-16 Seoul

K-40 Cheju-do Island
K-46 Hoengsong
K-47 Chunchon
K-55 Osan

The "K" stood for Korea in the designation. The US Army also had "A" (Army) airfields and "AE" (Army Expedition) airfields. The USMC had designated their fields by "X" early in the conflict but later took the Navy designation "K".

The Seabees took on many projects during the Korean Conflict, including building airstrips, clearing mined tunnels, and repairing ships.

CBD-1804. (Construction Battalion Detachment-1804), as organized in 1951 at Atsugi, Japan where MCB-2 was at the time,  was deployed to K-3, Pohang, South Korea in 1951.    CBD-1804 was operational at K-3. Later, CBD-1804 was re-designated CBMU-1 while in Korea.  The CBMU-1 unit, (Construction Battalion Maintenance Unit -1), was later re-designated CBMU-101 while at K-3. 


(Source: http://www.history.navy.mil) 

In June 1950, following the invasion of South Korea by the armies of communist North Korea, the Seabees found themselves at war again. As part of the United States contingent of the United Nations force, they rose to the challenge in the tradition of their "Can Do" predecessors. By a calling-up reservists, their active-duty force was expanded to more than 14,000.

On 15 September 1950 U.S. troops landed at Inchon in what has come to be known as one of the most brilliant amphibious assaults in history. Seabees (ACB-1) achieved renown as the men who made it possible. Battling enormous thirty-foot tides and a swift current while under continuous enemy fire, they positioned pontoon causeways within hours of the first beach assault. Following the landing, the incident known as the "Great Seabee Train Robbery" took place. The need to break the equipment bottleneck at the harbor inspired a group of Seabees to steal behind enemy lines and capture some abandoned locomotives. Despite enemy mortar fire, they brought the engines back intact and turned them over to the Army Transportation Corps.

In October, Seabees (ACB-1) ran their pontoon structures ashore again and set up another operating port at Wonsan. When the strenuous harbor construction and camp operations ceased to fill their days, they branched into the unusual tasks of inspecting North Korean armament on an abandoned mine-layer, clearing mined tunnels, and performing repair work on nearby ships.

When the Chinese Communists joined the retreating North Koreans to launch another full scale invasion of South Korea, the Seabees were compelled to redouble their efforts -- this time to help the retreating U.N. forces. At Hungwan, Wonsan, and Inchon, where Seabees had been instrumental in putting U.N. forces ashore, Seabee pontoon causeways were now loaded with troops and equipment going the other way.

By February, however, the tide turned once again and the Seabees returned to Inchon for another landing. They found their previously constructed harbor facilities in a state of ruin, but, miraculously enough, some of their sturdy pontoon structures were still in place. After a rapid repair job, men and equipment streamed ashore again.

Seabee participation in the Korean War was certainly not limited to amphibious operations. Another of their outstanding contributions was in that specialty of their World War II predecessors -- airfield construction. Seabees could be found throughout the war zone constructing, repairing, and servicing the K-fields of the various Marine Air Groups. The Seabees were broken up into numerous detachments and each was assigned to an airfield designated with a "K" number, such as K-3 at Pohang, K-18 at Kimbo, and K-2 at Taegu.

Keeping the planes flying was an arduous and often dangerous task. At one small airstrip on the 36th Parallel, chuck holes were opening up in the failing concrete faster than they could be repaired. As it was absolutely vital that the field remain open, the undaunted Seabees graded, poured, and patched one side of the runway while bomb-laden aircraft continued to fly off the other side.

Seabee relations with the Marine Corps were further cemented by a group of nine Seabees who kept a 21-mile stretch of road open between an isolated Marine intercept squadron and its source of supplies. They worked round-the-clock in five-below-zero temperatures to successfully fulfill their promise to rebuild any damaged bridge within six hours.

One of the most incredible Seabee feats (ACB-1) of the war took place on the small island of Yo in the Bay of Wonsan. In communist hands again in 1952, Wonsan was a key supply and transportation center for the enemy. As such, carrier-based aircraft strikes against Wonsan and points deeper in the interior were numerous and constant. Planes were hit by enemy fire daily leaving their pilots with the unhappy choice of either ditching at sea or attempting to land in enemy-held territory. The need for an emergency airstrip was critical and, under the code name Operation "Crippled Chick," a detachment of Seabees (ACB-1) came to the rescue. Put ashore on Yo Island, they were given 35 days to construct a runway. Working under constant artillery bombardment from neighboring enemy positions, they managed to complete the 2,400-foot airstrip in only 16 days. By a prearranged signal, "Steak is Ready," the Seabees signaled that the job was done, and nine damaged aircraft landed on the new field that same day.

The rapid demobilization that followed the Second World War was not repeated after the signing of the Korean Armistice in July 1953. Crises in Berlin, Cuba, Africa, South America, and especially in Southeast Asia created the necessity to maintain military strength and preparedness. Seabee Reservists had helped meet the Korean crisis, but the onset of the Cold War had indicated the need for a basic reorganization of Seabee capabilities as well as for increased Seabee numbers. Between 1949 and 1953, 13 battalions of two distinct types were accordingly established. The new establishments signified a gain in greater battalion mobility and specialization. The first type, the new Amphibious Construction Battalions, were landing and docking units. An integral part of the Fleet Amphibious Forces, their mission was to place causeways and ship-to-shore fuel lines, construct pontoon docks, and perform other functions necessary for the expeditious landing of men, equipment, and supplies. Naval Mobile Construction Battalions constituted the second type. They were responsible for land construction of a wide variety, including camps, roads, tank farms, airstrips, permanent waterfront structures, and many other base facilities.

Seabee battalions of the Korean era:

MCB-1 was activated at Davisville, RI, in August, 1949. Did not serve in Korea.

MCB-2 was activated at Port Hueneme, CA, in June 1950. Did not serve in Korea.

Formed and staged from Advanced Base Depot, Port Hueneme, California:

MCB-3 was activated in July, 1950.

MCB-4 was activated in __?_1950.

MCB-5, MCB-6, MCB-7, MCB-8 and MCB-9 were activated later during the Conflict but did not serve in Korea.

MCB-10 was formed in October, 1952.

MCB-11 was formed in July, 1953. Both Ten and Eleven did not serve in Korea.

CBMU-1 was activated in July, 1952, and served in Korea.

CBMU-2 was activated in October, 1953, and served in Japan only.

(Reference: “U. S. Navy Seabees Since Pearl Harbor”, Jay Kimmel, 1995). 

A Korean-era project that occupied many Seabees was begun in the Philippines in 1951. It was at this time that the Seabees began building the naval base there at Cubi Point. Three thousand Seabees from MCB-2, 3, 5, 9, and 11 spent the next five years expending over 20 million man-hours building the installation for the United States Seventh Fleet. (“Mobilizer, May-June 1992, p. 13).

Reserve Seabees

The Seabees were created in WW II and their ratings were considered Reserve ratings. In fact, all World War II Seabee construction personnel were designated “USNR”. All Seabees remaining on active duty continued in that status before the Navy made them a permanent part of the Navy and classified construction ratings as permanent “USN” in 1947. (Source: Navy Historical Society web page, Seabee History).

The Naval Reserve had existed since 1916 but the Seabees were not a part of the Naval Reserve as the Seabees had been created during World War II. After a period of post-war review the Seabees became an official part of the Naval Reserve on December 31, 1947. There were several factors. World tensions resulted in more concern that a future conflict would result in the need for activation of reserve personnel of all services. In 1947 the Truman Doctrine announced U. S. intention to support any peoples resisting “subjugation … or outside pressures.” The reserve forces of all other services were increased and so were those of the Naval Reserve.

Just prior to the Korean Conflict the Naval Reserve had 316 Naval Reserve Training Centers, twenty-one Naval Reserve air stations, and 104 ships assigned exclusively to Naval Reserve training. The Reserve Seabee program was organized consisting of Seabee Companies each consisting of 4 officers and up to 40 enlisted men at a Naval Reserve Training Center. In 1951 the total organized allowance of 234 Seabee Companies was about 1,100 officers and 9,000 enlisted men. The Seabee Companies were organized in about 200 Naval Training Centers. Reserve Seabee Companies were not deployable units, therefore, no Reserve Seabee units served in the Korean era. (Source: “Citizen Sailors: The U. S. Naval Reserve in War and Peace”, W. Kreh, 1969; Naval and Maritime Chronology)

The effect of the Reserve program was felt when the Korean Conflict began. The Navy called on the Seabee Reserve for skilled construction men to bolster the regular force. Within a few weeks volunteers from across the country had been activated and had proceeded to their ports of embarkation. Within a few months more than 60% of the Seabees on active duty were Reservists. Many of them were veterans of World War II having joined the reserve program since 1947. Later in the war, when over 10,000 newly enlisted Seabees had been added to the force, the percentage of Reserves in units dropped to below 50%. (Source: “Shield of the Republic”, by M. Isenberg, 1993).​

Naval Reserve

“During the Korean Conflict the Naval Reserve mobilized about 185,000 members. About 7,500 of those were Reserve Seabees. Of the 230,000 officers and enlisted added to the rolls during the first eight months of the Korean Conflict, half were Reservists, and of these, 70 percent were at sea, doing their jobs, by March 1951. Overall, Navy manpower increased by 60 percent, and the number of combatant ships went up by 50 percent. By November 1951 fully 75 percent of all Navy air sorties over Korea were being flown by Reservists.” (Source: “Shield of the Republic”, by M. Isenberg, 1993).

Over 1,177,000 Navy personnel served in Korea. Of these, 458 sailors were killed in action, 1,576 suffered wounds, and 4,043 succumbed to injury or disease. Without the dedicated service and sacrifices made by Navy men and women, ashore and afloat, the United Nations would not have been able to preserve the independence of the Republic of Korea or achieve the armistice agreement with the Communist belligerents that ended the conflict on 27 July 1953. (Source: The Navy, Naval Historical Foundation, 2000; verified by the 1989 World Almanac).


Navy Seabee Units in Korea

1950 – 1953  

Unit Designation    Location   Commanding Officer    Strength   Deployed to / fm

ACB-1 Inchon Landing, Wosan, (1stMarine Division); Inchon (second) (while assigned to 7th Fleet 500 (est.)

??? 1950 - Sept 1950

ACB-1 CDR A. T. Roth, CEC, USN

Oct 1950 - Nov 1951
ACB-1CDR J. F. Staniumas, CEC, USN

Nov 1951 - Jan 1953
ACB-1 CDR W. C. Bowers, CEC, USN

Jan 1953 - Oct 1953

ACB-1 LCDR G. L. Moeller, CEC, USN

Oct 1953 - Feb 1954
CBD-1804 K-3 LCDR Cameron W. Lee, CEC, USN
32+2 (est.)

CBMU-1 K-3 LCDR Cameron W. Lee, CEC, USN 357 (est.)

CBMU-101 K-3 CDR O. E. Forbess, CEC, USN * 594 (est.)

Detail K-2

Detail K-3

Detail K-6

Detail K-13

Detail K-18

Detail K-55

30th NCRSubic Bay, Philippines est.)
??? - ???

Airfields in Korea:

There were about 40 "A" fields, 70 "AE" fields, and 40 "K" fields with 7 of those 40 also designated as "A". For example, Taegu 2 was "K-37" but also "A-3" and "K-38" was also "A-34". (Ref: Airfields, "Encyclopedia of the Korean War", by S. C. Tucker).

Airfields with Seabees in Korea:

K-2, Taegu,

K-3, Pohang,

K-6, P'yong Taek

K-13, 1st MAW USMC site (Corsairs and AD’s) (MAW = Marine Air Wing)

K-18, (Seoul), Kimpo

K-55, Osan

(c) Copyright 2002 by Larry G. DeVries (of all original work). All rights reserved.

With all respect to Pat Morris, I would like to provide the web site address to his expertly organized web site, however Pat died a number of years ago and all of his pictures and Korean War Seabee information was lost and is no longer available.  I did copy some of Pat's web site before it was closed:

"The first Seabee unit to be attached to the First Marine Air Wing at K3 Korea was CBD-1804. There had been other Seabees on temporary duty there but CBD-1804 was the first unit of Seabees to be attached to the Air Wing. In October of 1951 the inaugural group of CBD-1804 flew into K3 from Atsugi, Japan under the command of LTCDR Cameron Lee. Thanks to Charles Godshall, a part of that first group, for providing pictures of the first Seabees attached to the First Marine Air Wing in Korea. In the Summer of 1952 the name of this group was changed to CBMU-1 and later, in October of 1953, it was changed to CBMU-101.   

LTCDR Cameron Lee was the first Commander of the CBD 1804 inaugural group that arrived in Korea in 1951. The people that knew him said he was well liked and respected by the men to the point of them playing practical jokes on him.   One story goes that a Jeep was stolen from a high ranking Marine officer, painted yellow, and was "given" to LTCDR Lee." 


Seabees remember Korea - special commemorative issue 2003


Korean War - History of CBD-1802 & 1804

by R. B. Howard SV-2


On 8/07/51, I was directed to report, at 0800 to a LTCDR Randell in the Port Hueneme Admin, annex Bldg. I arrived and found a number of other men that I had served with previously on Adak in Alaska and Guam. The group were mostly draftsmen & land surveyors. We were interviewed individually by Cdr Randell which was a little unusual. During my interview, he read from my service record and said something like, for a man who just turned 21 you have a lot of experience. How would you like to join me on a trip to some where north of the Philippines. I replied, that if he was asking, my answer was no, since I was happy being in Port Hueneme, after 2-1/2 years of Islands. 

About the end of Aug. ‘51, CBD 1802, including me, left Port Hueneme on the train to San Francisco and on to Travis AFB. The Detachment consisted of 24 enlisted, 2 chief petty officers, Randell & Ens. Hubbard. We departed from Travis AFB located at Fairfield, CA on a charted civilian air line for Hawaii, Wake Island and then on to Japan. We landed in Japan & immediately departed again on a Navy aircraft (MATS) landing at Naha Okinawa, an Air Force base. 

We did various preliminary engineering studies from soundings at Bucknerville Bay, & topographic surveys of an abandoned USN air field. We lived at an Army Post on the east coast of Okinawa. We even survived a Typhoon. We left Okinawa in late November and flew to Atsugi, Japan where the enlisted men TAD to MCB-2, the two chiefs and both officers worked in Naval District headquarters in Tokyo.

On December 26, 1951 16 men including Chief John Cooper were TAD to 1804 at K-3 in Korea. (K-3 was an air field constructed in the late 1930’s, by the Japanese). The air strip was about 5700 feet long and about 25 feet lower in the middle than at either end. The field was located on a small plateau at the base of a mountain range.  MAG-33 (Marine Air Group-33) flew ground support sorties for the front-line infantry about 60 miles north. MAG-33 operated F-9-F Panther Jets and AD ground support type prop driven air craft. Three flights of 21 planes each were flown by each type aircraft every day.

This area had been taken by the North Koreans during the early days of the war.  The UN troops moved them out of the Pohang area.  The mountains were by-passed and we knew there was a number North Koreans remaining in these mountains. Pohang was mostly leveled.  However, both sides had preserved the air field for later use. Operating jet aircraft from this field was not easy. Taxiways were mostly dirt and the run-up areas used steel mating (Marston Mats).  The runway was made of concrete which had been hand-finished leaving ridges 5 to 6 inches high. (Very hard on the aircraft small tires.) 

 Our job was to do a cross-section and topographical survey of the area and the gullies on either end. With this data, plans were developed to extend the runway and generally up-grade the field. We finished our work about 3/1952 and were flown back to Tokyo where we remained for 10 days. 

The men of CBD-1802 were made up of a mixture of reservists who had been called to active duty for 12-24 months at the beginning of the Korean War and regular Navy who were serving one year involuntary extensions. 

The Two officers and a number of the enlisted men had almost completed their reserve recall time and were sent back to the states. About seven of the enlisted men and Chief Cooper were transferred to Guam to work in CBD 1803, until extensions and reserve commitments were served.  In my case I was discharged on 6/12/52, having enlisted on 6/29/48 for three years. MATS from K3 to Japan, then to Guam