They Were Expendable (1945)

Storyline:
After a demonstration of new PT boats, navy brass are still unconvinced of their viability in combat, leaving Lt. "Rusty" Ryan frustrated. After the attack on Pearl Harbor, however, Ryan and his buddy Lt. Brickley are told they can finally take their squadron into battle. The PT boats quickly prove their worth, successfully shooting down Japanese planes, relaying messages between islands, and picking off a multitude of enemy ships.