The Seabee Museum Pushing Forward ACB to UCT

As we move into fall, the U.S. Navy Seabee Museum staff reflects on the year—(what did you do over the summer?). Earlier this year we opened a new exhibit in the Changing Gallery: The Impossible Takes a Little Longer, Celebrating the Seabees 75 years through 75 objects. Then over the summer we finished a complete renovation of the Humanitarian exhibit with artifacts and a storyline describing the many different aspects and time periods in which Seabees have provided humanitarian assistance while traveling the globe. Moving forward, the museum staff recently renovated the Amphibious Construction Battalion (ACB), and Underwater Construction Team (UCT) exhibits.


Humanitarian exhibit

During the simultaneous renovation of both exhibits: we elaborated on the ACB and UCT storylines, added new and enhanced exhibited artifacts with new cases, and relocated artifacts. Relocating most of the artifacts took one, maybe two staff members, though day- one of the overhaul included the staff pushing and pulling a 2,000-pound T-6 Pontoon from the WWII Atlantic Theater Gallery across the Grand Hall and placing it in the middle of the ACB exhibit. Moving the pontoon into the exhibit area enabled us to tell a more complete ACB story with text panels and a 12-foot long timeline detailing their history from WWII to the present, and the transformation of pontoons and lighterage.

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With a more complete story, we highlighted the scientific part of ACB beginnings and continued that into the Underwater Construction Teams’ story and their contribution to the Ocean Facilities Program and the Naval Civil Engineering Laboratory (NCEL). Within these stories, we showcase NEMO (Naval Experimental Manned Observatory), underwater construction tools, and the transition of diving masks and tools from WWII to the present.


UCT exhibit

Present plans as we head into winter: the Morgan Wilbur OEF (Operation Enduring Freedom) Seabee art exhibit will be closing in 2-months during the first week of December and heading back to the East Coast. The Exhibit Team is preparing to move the Transition Years (1975-2001) exhibit to North Gallery and refresh the Civil Engineer Corps Gallery with new panels, artifacts, and interactive programming.


Three of the paintings included in the Morgan Wilbur OEF exhibit.


What is a pontoon and what are they used for?

What percentage of the Earth is covered with water?

The oceans hold what percentage of the Earth’s water?


That One Time the Seabees Found a Submarine

By: Julius Lacano

Historian, US Navy Seabee Museum

On September 1, 1942, the Seabees of the 6th Naval Construction Battalion (NCB) got to work completing the unfinished Japanese airfield at Lunga Point, on the Island of Guadalcanal, that would become to be known as Henderson Field. Captured by the 1st and 2nd Marine Divisions less than a month earlier, this airfield had been a Japanese stronghold threatening Papua-New Guinea, Australia, and the shipping lanes that connected them to the United States and New Zealand, making it a vital strategic target for the Allies.  The Seabees would spend their time clearing and grading the center of the airfield, adding 1,300 feet to the existing air strip, and improving it for use by heavy bombers, in addition to fighter aircraft.  The Seabees had to excavate and refill many portions of the airfield due to the soil in the area being waterlogged muck.  Throughout all of this, the Seabees were under nearly constant air and artillery attack, which created the need to repeatedly fill in craters, regrade the ground, and re-lay Marston matting.


Henderson Field after completion in April, 1943

To the Japanese, this location was no less important and their determined struggle to recapture it serve as a catalyst for one of the most important campaigns of the WWII. The Imperial Japanese Navy and the US Navy fought in five major engagements in the waters north of Guadalcanal.  The Japanese won two of the three battles, but these victories rang hollow due to their inability to counter the Allied offensive, resupply and reinforce their dwindling garrison on Guadalcanal, and recoup their losses in men, ships, and aircraft.  Though the US Navy suffered one of the greatest defeats in its history at the Battle of Savo Island on August 8-9, 1942, it used the experience to make sweeping operational and structural changes that impacted its ability to battle the Japanese throughout the rest of the war.  The site of these naval battles became known to the men that fought there as “Iron bottom Sound” due to the over 50 Allied and Japanese naval vessels and dozens of aircraft that now rest on the bottom.

Battle_of_Savo_Island_map_-_disposition_of_forces (1)

Map showing Iron Bottom Sound, the disposition of force during the Battle of Savo Island, August 8-9, 1942, as well as the location of the Japanese mini-sub base, and the approximate location where the submarine was located.

While the Japanese used large warships to fight the Allied naval forces, they also used small two-man midget submarines.  Based at a small installation on the western side of Guadalcanal, or carried to the island by larger submarines or surface ships, these submarines were sent out to attack the ships of the Allied fleet that sailed the waters north of the island.  One of these sunken submarines was found by a group of surprised Seabees when the Higgins boat they were on hit the submarine’s periscope.  While initially thought to be a naval mine, the Seabees soon realized they had run into a Type A Ko-hyoteki-class submarine in 20 feet of water, 300 feet offshore near Tassafaronga Point, between the landing beaches near Henderson Field and Cape Esperance, located on the northwest shore of Guadalcanal.

The Seabees were determined to get the Japanese submarines out of the water. A small reconnaissance team, led by Chief Machinist’s Mate Robert E. Mitchell, donned repurposed gas masks attached with rubber tubing to a compressor and investigated the submarine and reported it to be in perfect condition, lying right side up, and still armed with two torpedoes. The Seabees tried to pull the submarine out of the water. Carpenter’s Mate First Class (CM1) Ralph D. Andrews and Boatswain’s Mate Second Class (BM2) George U. Ainsworth spliced together several sets of rigging made from one-inch cable and attached their ends to the front and back of the submarine and the other ends to tractors driven by US Marines on the shore.  After multiple attempts to free the sub using the rigging, it was found to be stuck fast to the bottom.

Undeterred, the Seabees decided to resort to other methods.  CM2 Harlow S. Ballard and CM3 Edward R. Cabana placed eight sticks of dynamite under the submarine to help dislodge their prize.  After clearing the area, the dynamite was detonated and the submarine was unsurprisingly freed from its sandy grave.  The submarine was then pulled out and beached near the wreck of the Japanese transport ship Yamazuki Maru.  After a thorough inspection of the submarine by US Navy officers, the unknown submarine became a “must-see” among the Allied personnel stationed on the island.


The story of the submarine, after its discovery by the Seabees, has been lost to history.  Today only four of the 101 submarines of this type remain in existence: One in Australia, one in Texas, one in Japan, and one at the US Navy Submarine Force Museum, in Groton, Connecticut (another one of the official US Navy museums operated by the Naval History and Heritage Command).  While the US Navy Seabee Museum does not have a real submarine in its collection, the museum does have the archival material about their find on Guadalcanal which made the research for this article possible.


HA-8, one of four Type A ko-hyoteki class submarines in existence.  This submarine is part of the collection of the US Navy Submarine Force Library and Museum in Groton, Connecticut. Like the US Navy Seabee Museum, the Submarine Force Library and Museum is a constiuent museum of US Navy History and Heritage Command.


Vocab List

Garrison: Troops stationed in a given area to defend it, or to use it as a home base.

Beached: Hauled up and stranded on a beach.


Carl Milford Olson: “An Outstanding Example of an Engineer and an Officer”

By: Julius Lacano

Historian, US Navy Seabee Museum


Lt. Carl Milford Olson

On September 9, 1943, Seabees belonging to Construction Battalion Detachment (CBD) 1006 approached the Italian mainland near the town of Salerno to take part in the Allies’ first assault onto mainland Europe.  Unlike the invasion of Sicily that previous July, the Allies did not achieve the surprise they were hoping for, and the Germans were waiting.  The men of CBD 1006 took on the greatest share of Seabee assistance given during the landings and suffered greatly because of it, suffering 28% casualties.

Among the thousands of Seabees and Allied soldiers desperately fighting to gain a foothold was Lt. Carl Miford Olson, a native of St. Paul, Minnesota and an enlisted Navy veteran of WWI where he served as a radio operator.  After the war, he attended the University of Minnesota and received a BS in Civil Engineering.  In the years prior to WWII, he worked as a draftsman in Chicago, ran his own architectural firm in his hometown of St. Paul from 1933-1941, and worked for a large engineering firm that had a contract building weapons and munitions plants for the US military.

In 1942, the 42-year-old Olson once again volunteered to serve his country and received his naval commission as an officer in the Civil Engineer Corps (CEC) in February, 1943.  From the US, he deployed across the Atlantic with the rest of CBD 1006 as Officer-in-Charge of a causeway construction platoon. He and the men under his command took part in Operation Torch, the invasion of North Africa and Operation Husky, the invasion of Sicily.  While attached to CBD 1006, he used his engineering experience to develop many of the fittings and connections, known as “jewelry” that were used to link pontoons together.  In fact, the ramps that were used on rhino ferries to unload cargo and vehicles were called “Olson Ramps” after their designer.


Map of the Landing Zones.  The British, along with Lt. Olson and the majority of CBD 1006, landed on the northern landing beaches, while the Americans invaded through the south.

The troops storming the beaches on September 9 were greeted by a loud message in English from the German defenses: “Come on in and give up. We have you covered.”  Undeterred, the landing craft and landing ships moved ever closer ready to release their cargo of men and war machines into the coming fray.  The German gunners near the beaches attacked the men with concentrated machine gun and artillery fire, while German aircraft bombed and strafed the beached and attacked the ships of the invasion force.  On September 10, Lt. Olson and his men were offloading men and equipment when a bomb struck their pontoon killing him and two of the men under his charge instantly.  All total, the Seabees would lose seven men and one CEC officer to enemy fire during the invasion. Despite this, the Seabees completed their objective and unloaded 11,500 vehicles and assisted thousands of men to shore earning the Navy Unit Commendation for their efforts.  Despite fierce resistance, the Salerno operation proved to be a success and allowed the Allies to reach the Italian city of Naples on October 1.

His death affected the unit greatly and a proclamation written by his fellow officers described him thus: “Lt. Carl Milford Olson, CEC, USNR, has by his attitude of service and friendship to all, and strict devotion and patriotism to his country won both the professional and personal friendship of all the officers and men…He was an officer and a gentleman. He died a hero’s death in defense of his country and its principles during the invasion of Italy.” Olson, though initially buried at Salerno, now lies in Ft. Snelling National Cemetery in St. Paul, Minnesota. In commemoration of Olson, the Navy named the headquarters of the now disestablished 1st Naval Construction Division at Joint Expeditionary Base Little Creek-Fort Story, Virginia the Lt. Carl Milford Olson Building, in 2012.  Among the panels on the building’s quarterdeck is a memorial to Olson which contains letters of condolence to Olson’s family from President Franklin D. Roosevelt and Secretary of the Navy William Knox, along with reproductions of his medals, including the Purple Heart he was awarded posthumously.  This serves as a fitting tribute to Olson, who was described by his Commanding Officer, Lt. Cmdr W.A. Burke, as: “an outstanding example of an engineer and an officer.”

The mission of the United States Navy Seabee Museum (USNSM) is to ensure that the construction and engineering accomplishments of the Seabees and the Civil Engineer Corps to the Navy and the nation are not forgotten, remain relevant, and inspire as many people as possible.  At USNSM you can see examples of pontoon jewelry that were designed by Lt. Carl Milford Olson on display.