登陸艇
Fleet Landing Exercise Number Six was the first wartime exercise in amphibious training in 1940–1941. It became clear that the Navy and Marine Corps was in dire need for amphibious transports larger than destroyers as the 1st Brigade could barely send two thousand Marines to land in the Caribbean and only adequate experimental landing craft were provided. Landing craft included two tank lighters, two artillery lighters, twenty-five special landing craft, of which twelve were the Bureau type, and eight landing skiffs. Comparative tests showed the Higgins Eureka landing craft, the 45-foot tank lighters, and rubber boats to have been the best adapted to landing operations. As a partial response to this problem, H.M. Smith seized the newly developed destroyer-transport. During FLEX 6, his plan called for the to land Company A, 1st Battalion, 5th Marines via rubber boats during the night, at H-minus three hours, at a point away from the primary assault beach. This force would advance inland, seize key terrain dominating the proposed beachhead, and thus protect the main landing from counter-attack. They were the first unit to use the revamped "Manley". On 23 February 1940 it used rubber boats to execute an assault landing against Culebra. In 1940, patrols were successfully infiltrating ashore and reporting information and became an accepted doctrine in amphibious reconnaissance.