Complex sentence: Having already been attacked once, they moved further out into the Atlantic to try and avoid the German Air Force, but a Junkers 88 appeared overhead at 07:30 and approached them at low level for a closer look.
Split into simpler sentences: Having already been attacked once, they moved further out into the Atlantic to avoid the German Air Force. A Junkers 88 appeared overhead at 07:30 and approached them at low level for a closer look.