In a port somewhere in England, cranes swing combat vehicles and supplies aboard an LST (Landing Ship, Tank) for transport to the D-Day beachhead.  Combat-loading a ship was a job for a highly-trained specialist, since every inch of shipboard cargo space had to be efficiently used, and items that were needed first had to be loaded last.  In this scene, combat-loaded trucks are shown entering the LST’s cargo deck through its open bow doors.