With first light on 20 November Rommel began to concentrate his forces in the area around Sidi Omar and in the early morning moved 21st Panzer Division firstly towards Sidi Aziz and then swung it southwards; but the panzers had not driven far when they ran out of fuel and were forced to halt. Not until the evening did the supply trucks reach the area in which the division was stranded and then there was further confusion when a column, sent out from the main group to find 5th Panzer Regiment and to refuel its vehicles, was prevented only at the last moment by a search unit equipped with wireless from driving into a British laager. The 15th Panzer Division was moved from its position north-east of Sidi Rezegh and was sent roaring along the Trigh Capuzzo in a search and sweep operation, looking for the British armour supposed to be attacking the German reconnaissance battalion. It found neither. South-west of Gasr el Arid the division then swung in a great arc southwards and then south-westwards towards Sidi Aziz to support 21st Panzer. At 15.00hrs 15th Panzer attacked Gabr Saleh having the panzer regiment as point unit, closely supported by the field and flak artillery, and with 15th Infantry Brigade to the right rear and 200th Regiment on the left rear. In the course of its advance it came up against 80 British armoured fighting vehicles of 4th Brigade, but these could not halt the advance and by dusk the leading elements of panzer regiment were on the Trigh el Abd. British counter-attacks came in on the western and then on the south-eastern flanks but the fighting died away and the German group lay with the British tanks, forming a half circle around them and at some miles distant.
By the time that darkness halted the fighting of 19 November, the 4th Brigade had lost another 55 vehicles so that the 165 tanks with which it had begun the offensive had been reduced to only 68 runners. To support the 4th Brigade in the battle it had been righting against 15th Panzer, the High Command had ordered 22nd Brigade from Bir el Gobi back to Gabr Saleh but it was dark before the appointed area was reached and not until dawn on 21st had the whole unit regrouped north-west of its objective. Help to the struggling 4th Brigade had been offered by the New Zealand division but this was refused under the terms of the Army Operations Order which decreed that 13 Corps was not to be involved in tank battles.
The 20th began and continued as a day of mounting crisis for the Germans, particularly for those defending Sidi Rezegh, for they were righting desperately to prevent the breakthrouglj to Tobruk. The battle swayed to and fro as the tank attacks swept down upon the infantry of 90th Light Division and were repulsed time and again by a screen of anti-tank and 8.8cm guns. During the afternoon the Luftwaffe sent in fighter planes and Stukas to attack and break up the British tank spearheads; splitting up and driving these back to the heights at the southern edge of the airfield. The hard-pressed German infantry had a short respite. To the south of Sidi Rezegh the Ariete Division defending Bir el Gobi was coming under increasing pressure from the advanced elements of 1st South African Division and could not prevent tha: unit from advancing north-westwards. On the eastern flank, in 13 Corps sector, a two-pronged assault to capture the Halfaya Pass came in but the New Zealanders, now aware that on their left flank hovered the menace of the panzer divisions, moved slowly northwards to reach the Trigh Capuzzo. The move was a slow one for the New Zealand division needed to be certain thai the panzers had been drawn against 30 Corps before a more rapid drive upon Tobruk could be made. In truth the British armoured presence had drawn upon it the German panzer force and it had suffered as a consequence, although it was still strong enough to pose a threat.
During the evening of 20 November Rommel worked out, in closer detail the plan to concentrate the Africa Corps and to use it to destroy the isolated and unsupported British armoured groups one by one. The tone of Africa Corps orders for 21 November, that an attack was to be launched into the rear of the British forces advancing from Belhamed, anticipated the urgency which was shown in wireless messages which went out at 04.00hrs ordering the attack to be put underway immediately. The British intentions had at las: been assessed and it was anticipated that an advance from Sidi Rezegh would be made in conjunction with break out attempts from Tobruk.
All through the night of 20/21st the fighting around Sidi Rezegh flickered and burst into fierce action. The infantry of 90th Light was forced farther and farther back from the southern edge of the high ground near Sidi Rezegh until it found that it was fighting back to back with the Pavia and Bologna Divisions. The Germans were defending themselves against the assaults of 7th Armoured Division while the Italians were seeking to stem the blows from the Tobruk garrison. Attack and counter-attack followed in a series of bloody, little battles. Slowly the 90th Light gave ground under pressure but then, to prevent the danger of an encirclement of Africa Corps, the 3rd Reconnaissance Battalion was ordered out of Army Group reserve and brought forward to the left flank of Africa Regiment of 90th Light. The reconnaissance troops roared forward in a desperate charge and drove back a British tank unit from the ground which it had won. For the moment, but only for a moment, there was a relief of tension.
To the east in 13 Corps area there was a disengaging movement and the Germans shook off the hold of 4th Indian Division and of 22nd Armoured Brigade which had moved up in support. Hidden by the rain and the poor visability of a cold November morning the Germans withdrew and left only rearguards to obstruct and to delay the advance of the Imperial troops.
The German panzer divisions now stood as a solid mass of armour between 13 Corps to the east and 30 Corps to the west and the whole battle line from Tobruk to Halfaya can be seen as an eight-layered battle. An encircling ring of Axis troops lay without the British defenders of Tobruk. At Sidi Rezegh was a layer of Germans and Italians facing the thrusts of 7th Armoured Division. Then came the might of the two panzer divisions and to the east of that concentration there was 13 Corps advancing northwards towards the Trigh Capuzzo. Other Axis troops held the embattled perimeter from Bardia to east of Sollum and on the eastern side of that beleagured place lay the last layer of the front - the 4th Indian Division.
A similar layered battle was being fought on a north to south axis, that is from Tobruk to Bir Hachim. The British inside the perimeter were surrounded by the investing forces, other elements of which were facing the British around Sidi Rezegh. Then came a lawyer of Italian troops of Ariete Division around Bir el Gobi facing the South Africans. Lastly came the layers formed by elements from Trieste Divisions striking out from Bir Hachim against the Indian Brigade thrusting towards Gialo.
The seriousness of the situation in which the British had been now placed was not at first realised and, indeed, did not become apparent until both panzer divisions began to roll up 7th Armoured Division from east to west. For the assault 21st Panzer Division took the right flank with Belhamed as its objective, while 15th Panzer Division on the left moved via Sidi Muftan towards Sidi Rezegh. The wide, armoured front of the two panzer divisions advancing side by side and followed closely by the batteries of 8.8cm guns, moved rapidly forward and drove before it scattered British units which it encountered. By midday the heights south of Sidi Rezegh had been reached and 7th Brigade's commander, appreciating the sudden danger, broke off his own attack and swung his force to meet the onrushing panzers. The defence of Sidi Rezegh airfield was then passed over to Support Group. The British tanks observed the panzer force passing across their front and firing from hull-down positions struck deep into the German flank. Once the shock of the first contact had passed a general melee developed and bitter battles were fought out between tank and tank, and tank and guns. Before long the British had settled down, had taken up all around defence against the Germans, and had prevented them from seizing the airfield. During the afternoon tanks encountered German trucks as they were replenishing their fuel and ammunition stocks and attacked these causing much panic and alarm. Night fell and the fighting tailed off leaving only the burning vehicles to illuminate the blackness of the night. The opponents drew back from each other. The two panzer divisions tired from the strain of fighting and of night driving, hoped to laager for the night but then came orders for them to change their positions and 15th Panzer Division was moved to Gambut while 21st Panzer Division proceeded to Zaafran.