In September 1939, Messervy was promoted to colonel and became a General Staff Officer Grade 1 of the Indian 5th Infantry Division, which was about to be formed at Secunderabad. In mid-1940, the division was sent to the Sudan to counter the threat from the Italian forces based in Italian East Africa. Messervy was appointed commander of "Gazelle Force". Created on 16 October 1940, it was a mobile reconnaissance and strike formation of expanded battalion size created from elements of 5th Indian Division. During the ensuing East African Campaign, Messervy commanded "Gazelle Force" with notable success, latterly attached to the Indian 4th Infantry Division. By 13 February 1941, the campaign had become static and Messervy's formation was disbanded.