The Guns of Navarone

In this WWII spectacle, British intelligence learns that two enormous guns have been installed on the Aegean island of Navarone. The long-range field pieces are capable of destroying any British fleet trying to sail to Kheros, near Turkey, where a large British force is facing annihilation unless it is evacuated. It's the job of Captain Mallory and a handful of men to land secretly on Navarone and dismantle the guns.