Complex sentence: After serving six operational patrols, "U- 751" was attacked on her seventh patrol, sinking a mere four days into her voyage on July 17, off the coast of Cape Ortegal in Spain by depth charges from a Lancaster bomber.
Split into simpler sentences: After serving six operational patrols, "U- 751" was attacked on her seventh patrol four days into her voyage on July 17. She was sunk off the coast of Cape Ortegal, Spain by depth charges from a Lancaster bomber.