Complex sentence: The town centre was hit by a V-1 flying bomb in 1944 with over 300 fatalities which devastated the high street, which was restored fully by the mid- 1950s.
Split into simpler sentences: The town centre was hit by a V-1 flying bomb in 1944 with over 300 fatalities. It devastated the high street, which was not restored to its former glory until the mid- 1950s.