Both Tobruk artillery commanders in April 1941 were British brigadiers. Brigadier Thompson commanded the field and anti-tank guns. He believed that the field artillery needed to be ready to fill the anti-tank role, so the guns were sited accordingly. Tobruk had 48 25pdr guns, 12-18pdrs, and 12-4.5in howitzers. Two field regiments supported the 20th Brigade in the south of Tobruk. The other two brigades each were supported by a field regiment.
Brigadier Slater commanded the anti-aircraft guns at Tobruk. He had "24 heavy and 60 light guns". There were four captured Italian heavy anti-aircraft guns while 43 of the 60 light guns were captured Italian. Their main duties were to provide anti-aircraft support to the Tobruk port. This was important because Tobruk being isolated, depended on supplies brought by sea. The Naval Inshore Squadron was now based on Tobruk. The squadron had been created during the initial campaign against the Italians.
For better or worse, Tobruk had captured Churchill's attention after the battle of 13 and 14 April 1941. Churchill was filled with suggestions about what Tobruk's defenders should do.
Rommel had hoped to stage another attack on 15 April, but the mainly Italian attack force was broken up by artillery fire and they abandoned their start positions. The Australians mopped up some 33 men hiding in a wadi. In another fight, Australians captured an Italian officer and 74 men. At about 5:30pm, another Italian attack had penetrated the wire. They had cleaned up the breach by 6:15pm. They captured 113 men, including two officers, and estimated that they had killed 250 men with artillery and automatic weapon fire. The number killed was probably an overestimate, but the number was still large. Troop movements seemed to indicate an attack against the 20th Brigade, but the attack did not happen.
On the night of 15-16 April 1941, four British destroyers from Malta attacked an Italian convoy heading for Africa. Three destroyers and five merchant ships were all sunk. The cargo was motor transport and tanks from the 15th Armored Division. This is based on the account in Vol.III of the Australian Official History.