Complex sentence: Most of 52nd Lowland Division and 1st Armoured Division embarked from The Beauman Division and Norman Force, which were composite formations, left on the evening of 17 June and the rearguard battalion was evacuated in the afternoon of 18 June.
Split into simpler sentences: Most of 52nd Lowland Division and 1st Armoured Division embarked from Beauman Division and Norman Force, which were composite formations, left on the evening of 17 June. The rearguard battalion was evacuated in the afternoon of 18 June.