Complex sentence: In March the 1st Parachute Brigade joined the division, and on 13 April the 6th Airlanding Brigade left the division but remained in Palestine as the 31st Independent Infantry Brigade.
Split into simpler sentences: In March the 1st Parachute Brigade joined the division. The 6th Airlanding Brigade left the division on 13 April, but remained in Palestine as the 31st Independent Infantry Brigade.