Complex sentence: Giles, wearing an Army Staff Sergeant's uniform that he had been able to steal while working in the laundry that was contracted to clean army uniforms, jumped aboard the boat through a freight hatchway below deck.
Split into simpler sentences: Giles, wearing an Army Staff Sergeant's uniform that he had been able to steal while working in the laundry that was contracted to clean army uniforms. He jumped aboard the boat through a freight hatchway below deck.