Complex sentence: On 4 September 1939, Cole, who had recently been released from prison, enlisted in the British Army (Serial No.1877989RE), and was assigned to an engineering unit, the 18th Field Park Company, part of the 4th Infantry Division.
Split into simpler sentences: On 4 September 1939, after recently being released from prison, Cole enlisted in the British Army (Serial No.1877989RE). He was assigned to an engineering unit, the 18th Field Park Company, part of the 4th Infantry Division.