"Calvert"'s next operation was in the Marianas, where she conducted diversionary landings off Tanapag Harbor at Saipan (15–24 June) and Tinian (24 July), an effort which added to the success of the main assault on Saipan. She returned to Pearl Harbor in August carrying 420 Japanese and Korean prisoners of war, and the following month was again westward bound to take part in the invasion of the Philippines.