The heavy anti-aircraft gun situation at Tobruk was something of a dilemma. Brigadier Slater's plan for harbor defense, the harbor barrage, was at odds with the lesson about fighting the guns at each site to defend themselves. The damaging raid on 27 April 1941 on the gun sites prompted new measures. The plan was to institute "camouflage, concealment, the construction of dummy positions and frequent changes of the defensive layout". The anti-aircraft gun brigade had a newly appointed officer to handle camouflage. One aspect was a construction project to build new gun sites. They also built dummy gun sites, with dummy guns, men, trucks, and ammunition dumps. During air raids, they exploded charges to make dummy sites look like they had firing guns. The existing gun sites had their defenses improved, including digging them deeper. Once these measures were added, losses from dive-bombing raids were greatly reduced.
About this same time, the situation near the frontier developed into a new crisis. During the German and Italian raids on 23 and 24 April near Fort Capuzzo, British prisoners were taken and interrogated. Based on information gathered, Rommel ordered the Herff Group to attack near the Egyptian frontier. The first move was taken near Capuzzo on 25 April. Support Group troops near Capuzzo were forced back towards Halfaya Pass, held by the 22nd Guards Brigade. Australian anti-tank gunners were providing support to the guardsmen. Bombing and strafing hit the pass late on 25 April. Herff's group attacked on the 26th. An Australian gunner fired high explosive shells at a German field gun and knocked it out. After darkness fell, the plan for withdrawal was put in effect. The 2/Scots Guards were holding a line "two miles west of Sidi Barrani". The men in the rear guards moved out from Halfaya Pass at 10:30pm. The rearguard at Salum left after midnight. Some of the Australian anti-tank gunners were assigned to the 2/Scots Guards. Some joined the battle group at Buq Buq named "Rushforce". Other Australian anti-tank gunners were spread out in various positions, including the Support Group headquarters, the 2/Coldstream Guards, 1/Durham Light Infantry, and the Free French Motor Infantry company. This is base on the account in Vol.III of the Australian Official History.