Sixty years ago, Milton Saxon was keeping watch on the island of Iwo Jima when he saw five Japanese soldiers climbing out of a burned-out hole in the middle of his Marine compound. He fired, and nothing happened. A second time, nothing. After the third misfire, he felt for his magazine clip. It was gone. "The safety and the magazine clip are about a half an inch apart on the carbine rifle," he said. "In my excitement, I pushed both and the clip fell into the bottom of a dark hole." With bullets whizzing above his head, he ducked down...