In 1940–1, he accompanied Orde Wingate on his mission to Abyssinia, and wrote a book of his experiences called "Guerrilla War in Abyssinia". On 6 March 1941 the Italian division won a victory; what they did know was that a much smaller force opposed them. Wingate set out to fool them in a game of deception: Allen remarked "Perhaps God fights on the side of great hearts and not of the big battalions." The tactic of surprise attacks behind unnerved the garrison at Debra Markos which scarpered in some disorder. He also met and recorded the activities of other Special Operations Executive (SOE) comrades Tony Simonds and Billy Maclean remarkable for their informality and eccentricities as their soldierly demeanour.