page_title: Seabees in World War II
section_title: The Atlantic theater
hierarchical_section_title: Seabees in World War II / The Atlantic theater
caption_attribution_description: U.S. Army vehicles roll ashore on one of the floating causeways of the "Mulberry" artificial harbor off "Omaha" Beach, 16 June 1944. The causeway had been erected by U.S. Navy SeaBees. Note the M3 half-track in the lead, towing a howitzer, and the Jeep behind it with a semi-circle marking painted on its grill.
context_page_description: When World War II broke out the United States Naval Construction Battalions did not exist. The vast oceans between the U.S and the enemy on both sides made the logistics of war a major concern. Rear Admiral Moreell completely understood the issues at hand. What needed to be done was build staging bases and create a military construction force to do build them to take the war to the enemy. The concept of Naval Construction Battalions had been developing at Bureau of Yards and Docks in the 1930s. The onset of war clarified to Radm. Moreell the need to be able to develop advance bases to project American power. The solution was to tap the United States vast pool of skilled labor. Put it in uniform to build anything, anywhere under any conditions and get the Marine Corps to train them. The first volunteers were skilled at enlistment. To obtain these men, military age was modified to take up to 50 years old. It was later found that several past 60 had managed to get in. Men were given advanced rank/pay based upon experience making the Seabees the highest paid group in the U.S. military. The first 60 battalions had an average age of 37.
context_section_description: "When the war became a two-ocean war, the Panama Canal became geographically strategic. The convergence of shipping lanes necessitated bases to protect its approaches.  Agreements in the Caribbean made it possible to obtain the sites needed. The Lend Lease Agreement also made sites available while existing bases were enlarged. Under the Greenslade Program naval bases in Puerto Rico, Cuba, and the Panama Canal Zone were all expanded. The construction program undertaken in Puerto Rico turned Naval Station Roosevelt Roads into the "Pearl Harbor of the Caribbean.  Construction on existing bases was done primarily by civilian contractors until late 1943 when CBs took over. In the Atlantic, the bases formed a line from Bermuda to Brazil. On the Pacific side of the Americas the U.S had bases from the Honduras to Ecuador.  The 80th(colored) CB upgraded Carlson airfield on Trinidad.  The 83rd CB cut a highway out of Port of Spain, that required moving a million cubic yards of material." "On the Galapagos Islands, CBD 1012 constructed a seaplane base with tank farm and did the same again at Salinas, Ecuador. Salinas would be the southernmost U.S. base in the Pacific.  In general, Seabees in this zone manned bases completed pre-war.  While not in combat zones they were necessary to the overall war effort."
  "North Africa was the Seabees first combat.  Landing with the assault in November 1942, they built facilities at Oran, Casablanca, Sifi and Fedala. Later they would build a string of staging and training areas along the Mediterranean including NAS Port Lyautey, Morocco."
  "Once Tunisia was taken the Seabees began a buildup at Bizerte. There they prepped steel pontoon boxes for their first use in combat at Sicily. This Seabee "innovation" was adapted for amphibious warfare. A pontoon box was standardized in size so multiple pontoons could be quickly assembled like to form causeways, piers, or rhinos.  As such they could be used to meet the exigencies of amphibious warfare. The beaches of Sicily were considered impossible for an amphibious landing by both the Allies and Axis.  The Seabees with their pontoons proved that was not true. The Germans were overwhelmed by the men and material that poured ashore over pontoon causeways.
  "Seabee causeways were used again at Salerno and Anzio. The Germans were prepared causing heavy casualties at both.  At Anzio Seabees were under continuous fire for an extended period. When Southern Italy finally fell the Seabees had one last task in the Mediterranean, Operation Dragoon."
  "Seabee operations in the North Atlantic began early 1942.  The first were in Iceland, Newfoundland, and Greenland.  These airfields and ports supported Allied convoys in the Northern sealanes. To complete the line of defence theses bases made, Seabees were sent to the UK. Londonderry, Northern Ireland, Lough Erne, Loch Ryan, and Rosneath in Scotland were transformed into depots, fuel farms, and seaplane bases to anchor the line.  Once completed the Seabees moved to South for Operation Overlord preparations. They built invasion bases from Milford Haven to Exeter and prepared for their multifaceted role."
  D-Day found Seabees amongst the first ashore as Naval Combat Demolition Units (NCDU). Their task was to remove beach obstacles built to impede amphibious landings. "NCDUs came under very heavy fire and worked until all charges were placed and detonated. The gaps created in the obstacles permitted the assault to hit the beach.  With the invasion force waiting, Seabees placed pontoon causeways over which the assault could access the gaps."
  "Seabees also brought their Rhinos. Rhino ferries were a motorized or towed variation of the modular pontoon boxes. With them, vast amounts of men and material went ashore.  Seabees also assembled offshore piers, and breakwaters into Mulberry A for the American sector.  It was a temporary port until French ports could be used.  Even after weather disabled the harbor Seabees continued to get thousands of tons supplies and troops ashore daily."
  "The liberation of Cherbourg and Le Havre provide
caption: U.S. Army vehicles transit a floating causeway built by U.S. Navy Seabees off "Mulberry A" at Omaha Beach
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