Complex sentence: Two were forced to turn back over the North Sea due to mechanical difficulties, and cloud over London caused the remaining bombers to divert to secondary targets at the Channel port of Folkestone and the nearby Army camp at Shorncliffe.
Split into simpler sentences: Two were forced to turn back over the North Sea due to mechanical difficulties. Cloud over London caused the remaining bombers to divert to secondary targets at the Channel port of Folkestone and the nearby Army camp at Shorncliffe.