The United States Naval Construction Battalion – better known as the “Seabees” – set about their job under strict conditions. At the time, in fact, personnel were absolutely forbidden to reveal their mission or location. This meant that the base was unknown in the U.S. at the time. As we shall see, however, the Japanese knew only too well that the Americans had occupied Ulithi.
Ulithi had no harbor as such, so it was the task of the navy engineers to build a massive floating base. And just a month after Ulithi had been captured, 6,000 personnel – including welders, electricians and carpenters – had already built a metal shop and floating dry docks. Pontoon piers were constructed, filled with gravel and sand, and secured to the shore and the coral below, creating safe anchorages.