On 7 November 1943, Berryman became acting commander of II Corps, a post which became permanent on 20 January 1944, superseding Vasey, whose 7th Division was diplomatically placed directly under Lieutenant General Sir Leslie Morshead's New Guinea Force. II Corps was left with the 5th and 9th Divisions. Berryman was promoted to lieutenant general on 20 January 1944. As in Syria, Berryman proved a hard-driving commander. In December 1943, II Corps broke out of the position around Finschhafen and began a pursuit along the coast. Whenever the Japanese Army attempted to make a stand, Berryman attacked with 25-pounder artillery barrages and Matilda tanks. Berryman was aware that seasonal changes were making the surf rougher and making it ever harder to operate the US Army landing craft (LCMs) and Australian Army amphibious trucks (DUKWs) that he depended on for the logistical support of his troops, but he realised that the Japanese Army's supply difficulties were greater than his own, and he gambled that if he pushed hard enough the Japanese would be unable to regroup and organise a successful defence.