The Axis forces near Tobruk were very much aware that an offensive was planned for 15 June 1941. They expected a fight starting at the first light of day on 15 June. They even planned an artillery barrage to be fired "at moonrise".
The 9th Australian Division had been holding Tobruk for about two months. While there had been no formal announcement, the men heard about the impending operation and the large numbers of British tanks that would be involved. There were practice exercises and knowledge of "administrative arrangements that gave the men knowledge of the impending battle.
The 9th Australian Division at Tobruk was to stay engaged and keep the Axis forces from moving to the frontier area. They would not move out from Tobruk unless the armored force managed to break through to Tobruk. If the circumstances warranted, the Tobruk garrison would break out to join the attacking force at Ed Duda, to the southeast. Apparently, late in the year, during the Crusader battle, a similar plan was executed.
General Morshead was very intent on making a big impact on the battle with his division. The problem was that he still would have to defend the Tobruk perimeter while trying to break out through the encircling force. There was no way that the Australians could take Ed Duda and make a strong position. The need to use his four brigades to hold the perimeter overrode that desire. He thought that he could still make an impact close to the perimeter.
The primary breakout from Tobruk would be executed by the 18th Brigade along with the 3rd Armoured Brigade. One battalion from the 26th Brigade would make an attack on the left. They would be operating near the Bardia Road. Something new was that a British commando company would land about six miles east of Tobruk. The commandos included Major Randolph Churchill. The right side of the attempted breakout would involve the 24th and 20th Brigades. There was some wishful thinking about what might be done if the Axis forces on the perimeter thinned out. The 18th Brigade had just moved into a reserve role, but now would be involved in an attack. They would push out two battalions that would establish a position from which artillery would be sited. Also from Tobruk, the 7th RTR would be involved with their 15 infantry tanks. They were part of the 3rd Armoured Btigade. Other tank units involved were the 1st RTR with "old" cruiser tanks. The 3rd Hussars would also be involved with their 19 light tanks, presumably Lt.Mk.VIb. The Kings Dragoon Guards was also involved with their 26 armored cars, almost certainly Marmon-Herrington Mk.II's. If the attack went well, one Australian infantry battalion would operate with the 3rd Armoured Brigade. This is based on the account in Vol.III of the Australian Official History.