After the 2/48th Battalion completed its training with the 9th Division at Cyrenaica, they were moved further along the coast to Gazala. Then, just as they began to dig in, the battalion was abruptly withdrawn to Tobruk in response to the German Afrika Korps' advance. They entered Tobruk on 9 April 1941, and spent the following eight months besieged by Axis forces. While there, Derrick acquired an Italian Breda machine gun and regularly led fighting patrols against both German and Italian troops. Although Derrick's bravery was noted during the siege, he wrote in his diary about his constant fear of dying.