Major developments from 4-5 December 1941 near Tobruk

A plan was proposed for the 2/13th Battalion to send a patrol to Outpost Plonk. If the enemy withdrew, they would set up an observation post. Outpost Bondi (also called Queen) was planned to be raided by another battalion. The 2/13th Battalion commander, now Major Colvin, had plans to use carrier platoons to strengthen the force  Before anything could actually happen, the brigade commander canceled the operations at 7:30pm.
The situation was changing. For example, the enemy forces that had been attacking Ed Duda had withdrawn and the enemy defenses near Ed Duda were abandoned. Reports came in that indicated that there was major movement of enemy forces from the east heading west. Tobruk sent out a group with anti-tank guns and machine guns to the Trigh Capuzzo. They fired on enemy columns driving west. There was a bottleneck between Ed Duda and the "next escarpment". Approaching columns were engaged and the situation got very tense, such that enemy attempting to pass through were "thrown into confusion."
23rd Brigade took command of all forces at Ed Duda. They were talking about assembling a battle group during the night to be ready to move west towards El Adem. As darkness approached, a Polish anti-tank gun group arrived. They reported that many outposts had been abandoned by the enemy. The local commanders responded by sending out patrols to occupy the empty outposts. Another disruption of plans occurred when XIII Corps canceled the advance to El Adem. The enemy withdrawal had caused the XXX Corps attack to be canceled.
From the German perspective, we learn that by morning on 4 December 1941, the Germans were going to push the east and destroy the British forces on the Egyptian frontier. They were also going to attack Ed Duda. Almost immediately, the attack on Ed Duda ran into trouble. There were four battle groups attacking Ed Duda. Mickl Group attacked from the west. Engineers from the 200th and 900th Engineer Battalions attacked from the south. The 8th Machine Gun Battalion attacked from the southeast. 90th Light Division infantry attacked from the east. The attacks were not made in concert and the only gains at all were those from the 8th Machine Gun Battalion. While the attacks on Ed Duda happened a British Jock Column raided and captured anti-tank guns and made prisoners.
Events of 5 December 1941 were remarkable. On the morning of 5 December, Rommel hoped to break the extension from Tobruk to Ed Duda and then push to Sidi Omar. By evening, Rommel had abandoned those operations. He concentrated German and Italian armored forces to be ready to fight XXX Corps. He abandonded all the ground from Tobruk east to the Egyptian frontier. There were also no German-Italian forces left on the east side of Tobruk. Rommel sent his armored forces to a position near El Gubi. The motivation for the changes is unclear, but the suggestion was that Rommel had read an intercepted message from General Ritchie to General Norrie. There are no German records that mention the message, but Rommel's changes were made shortly after the message was sent.
During the afternoon, Rommel ordered artillery and other unis from east of Tobruk to withdraw. Rommel had learned about the 2nd South African Division arriving at the Egyptian frontier. The 4th Indian Division was on the move on the Trigh el Abd. But the question remains "why did Rommel lift the seige of Tobruk? This is based on the account in Vol.III of the Austrsalian Official History.