Complex sentence: Reusing their bed sheet rope, they lowered themselves towards the ground; they were caught when the German guards heard the hobnailed boots of one of the escapees scraping down the outside of the guardhouse wall.
Split into simpler sentences: Reusing their bed sheet rope, they lowered themselves towards the ground. They were caught when the German guards heard the hobnailed boots of one of the escapees scraping the outside of the guardhouse wall.