From 4 to 8 April, "Aylwin" again was underway participating in further exercises before putting into Pearl Harbor. When the fleet sortied on the morning of the 18th, she ranged ahead of the departing battleships alert for possible "submarine" activity. Ultimately, "Aylwin" participated in the closing phases of Fleet Problem XIX, which had been conducted in three separate phases, each a small fleet problem in itself. As in Fleet Problem XVII, the exercises also tested the ability of the fleet to seize and hold advanced bases, indicating the Navy's Pacific-minded planning.