The Guns of Navarone came out in 1961 and, to my mind, is one of the greatest World War II films to ever come out of the 1960s and it seems to me that it must have been influencing Star Wars since the beginning. It tells the story of Keith Mallory (played by Gregory Peck) and a group of allied soldiers (including David Niven, Anthony Quinn, Anthony Quayle, and James Darren) as they work to destroy a pair of the biggest and well-fortified ship-destroying guns the allies have ever seen. If the guns aren’t destroyed within a few days, all of the allied soldiers being ferried through that channel for a rescue mission will be killed.
The story is entirely invented, there’s no island of Navarone, there were no British soldiers stranded on the isle of Keros, and the actors were all too old for the roles they were playing, but that doesn’t negate the charm and suspense of this effects laden picture.
Both A New Hope and Return of the Jedi have echoes of the plot. In the original Star Wars picture, the Rebel fleet must destroy the Death Star before it makes it within range of Yavin IV and it works out well. It inverts the tension with the bad guys attacking instead of passively hiding on an island. But Return of the Jedi is where the influence is felt the most.