Berryman's Duntroon class had not yet completed its military training. Major General William Throsby Bridges decided that regimental duty would rectify that deficiency, so he assigned the Duntroon cadets as regimental officers of the First Australian Imperial Force (AIF), rather than as staff officers. Cadets were given the choice of service in the infantry or light horse. One cadet, Lawrence Wackett, protested that he wished to serve in the technical services. When asked if they would prefer the technical services, twelve cadets, including Berryman, Beavis, Clowes, Vasey, and Wackett stepped forward. Berryman was commissioned as a lieutenant in the Permanent Military Forces (PMF) on 29 June 1915 and again in the First AIF on 1 July 1915. He was posted to Lieutenant Colonel Harold Grimwade's 4th Field Artillery Brigade of the 2nd Division Artillery, along with Vasey and Milford. Berryman embarked for Egypt with the 4th Field Artillery Brigade on the transport "Wiltshire" on 17 November 1915. In Egypt, Berryman briefly commanded the 4th Brigade Ammunition Column before it was absorbed into the 2nd Division Ammunition Column.