Crisp served during World War II in the 3rd Royal Tank Regiment, later writing two books documenting his experiences: "The Gods Were Neutral" and "Brazen Chariots", the latter of which is considered one of the classic memoirs of tank warfare. These books covered his combat during the early part of the war. "The Gods Were Neutral" describes the British retreat in Greece in the spring of 1941. "Brazen Chariots" covers the period from the summer of 1941 through Crisp's participation in Operation Crusader, up to his wounding. He was decorated for his bravery during the North African campaign and after being wounded there, nearly died several times from shrapnel in his skull as well as subsequent infection. Bernard Montgomery, commanding, intervened to restrict Crisp's decorations given the latter's disrespect for authority. Crisp ended the war with a Military Cross, Distinguished Service Order, and four "Mentioned in Dispatches".