The landing of the Polish Brigade at Driel forced the Germans to re-assess their troop dispositions. They feared that the new arrivals would cut the main road to Nijmegen, thereby trapping the 10th S.S. Panzer Division, or even attempt to retake Arnhem Bridge. Consequently some two thousand four hundred German soldiers, who would have been committed to the Oosterbeek battle, were instead relocated south of the Rhine to form a blocking line, Sperrverband Harzer, to counteract a move that would never take place. Despite this seemingly static approach to the battle on the southern side of the Rhine, the Polish Brigade were nevertheless heavily attacked throughout Friday; their positions were first heavily mortared and then assaulted by infantry, supported by tanks. Several outlying positions were overrun by the German advance, however the Poles clung fiercely to their positions and threw the enemy back from Driel.
The Germans recognised that the infantry and armour attacks made against the 1st Airborne Division on Thursday 21st September had yielded little success and cost them many lives. Rather than attempting to forcibly overrun the Oosterbeek Perimeter, they contented themselves with containing the British in the pocket and subjecting them to an intense and relentless artillery bombardment. By the end of the Battle, one hundred and ten artillery pieces, of varying types, were brought forward and sited around Oosterbeek for this purpose, and it was ensured that they were copiously supplied with ammunition. The 1st Airborne could do very little to resist this other than dig themselves deeper into their slit trenches and improve their protection from exploding shell fragments. One of the effects of such a heavy, ceaseless bombardment, apart from the casualties it caused, is the mental strain that it places on individuals, particularly on those who have had little or no sleep for several days. The destruction of Oosterbeek produced its fair share of shell shocked, or 'bomb happy' soldiers.
Another constant annoyance were German snipers, not just those who positioned themselves on the front-line, but also a high number of exceptionally brave men who, acting completely alone, used the cover of darkness to infiltrate themselves deep into British territory and installed themselves in the woodland in the southern half of the Perimeter. Those members of the Glider Pilot Regiment that were in the Division's reserve, who also frequently patrolled gaps in the British defences during the night, were usually given the task of stalking these snipers, a role in which they became highly effective.
The Germans around Oosterbeek proceeded to use these tactics of bombardment and annoyance until the end of the Battle. Infantry attacks still took place, but were far more cautious and targeted. The Germans hoped to chip away at the British defences piece by piece through the capture of buildings of strategic value. Their efforts, however, cost them dear and the Division remained largely unmoved; and any ground lost to the enemy was negligible. Tanks continued to roam around the front line, but not with the same impunity as they had in previous days when the Airborne troops had been advancing with precious little weaponry to deal with armour. In Oosterbeek, however, the Division's anti-tank gunners were well placed to ambush any vehicles that ventured a little too close to the British positions for their own good. Even so, the most effective killer of enemy armour was the hand-held PIAT, usually operated by lone individuals who ventured out into no-man's land to stalk tanks. Unfortunately, ammunition for this weapon became scarce very quickly.
The 1st Border were in some difficulty on Saturday 23rd September. Having been reinforced by sappers and paratroopers from the Divisional reserve, after two of their own platoons had been detached to become a part of Breeseforce (Map Ref 23), "A" Company (Map Ref 16) were heavily attacked by German infantry supported by self-propelled guns and tanks mounting flame-throwers. Nevertheless, both they and "C" Company, upon whom the blow also fell, were able to hold their positions and the enemy infantry were cut down by small-arms fire. "A" Company's ammunition was perilously short by this time, and so they stripped the German dead of their weapons and proceeded to use these throughout the remainder of the day to fight off a further three assaults. It has been estimated that, by this stage in the battle, half of the weapons being used by the 1st Border were German.
The Battalion's "D" Company (Map Ref 21) now occupied the most dangerous position of all as enemy infiltration to their rear had left them virtually surrounded and cut off from the remainder of the Division, however, despite their lack of numbers, they continued to resist.
On Sunday 24th September, the 2nd South Staffords in the Lonsdale Force area (Map Ref 2) fought desperately, with the help of the 1st Parachute Battalion's mortars, to repel a fierce infantry attack during the day. Two enemy tanks succeeded in breaking through their line when the only 6-pounder anti-tank gun in the area was knocked out, however one of the 1st Airlanding Light Regiment's 75mm Pack Howitzers was then brought forward and it destroyed one of the tanks and prompted the other to withdraw.
The RAF did not mount a re-supply mission on Friday 22nd September, as it was generally believed that XXX Corps would link up with the Division within the next few hours and so reinforcement was unnecessary. Having suffered so heavily during the previous days, this respite allowed the crews a chance to rest while the mechanics worked ceaselessly to repair their battered aircraft. The 1st Airborne Division, however, was not relieved on Friday, and so on Saturday 23rd, having received word that the supply situation was now critical, seventy-three Stirlings and fifty Dakotas of 38 and 46 Groups headed to Arnhem once more. This time the Allies provided a solid fighter escort, but flak continued to claim victims. On what was to be the last major re-supply mission undertaken, six Stirlings and two Dakotas were brought down and half of the aircraft involved were damaged. On Sunday and Monday, Dakotas of 575 Squadron, which had been specially relocated to Belgium, flew a small number of sorties to Arnhem for the loss of a single aircraft and no casualties, but once more their supplies failed to land on target.
The Royal Air Force had performed exceptionally well on these re-supply missions; flying slow and unarmoured transport aircraft through dense flak at very low altitudes, their performance has been described as some of the most courageous flying of the War. In all, two hundred and twenty-two aircrew and RASC despatchers lost their lives on these missions, and a further one hundred and twenty-three were taken prisoner. It was not the fault of these men that the dropping points were so difficult to find. Between the 18th and 25th September, the RAF dropped one thousand four hundred and eighty-eight tons of supplies over Arnhem, but of this less than two hundred tons reached the 1st Airborne Division. Much of the remainder served only to replenish German stocks. The vast majority of what was gathered in by the British were vital supplies of ammunition, food and medical equipment. There were, however, instances of troops recovering comparatively useless items, such as practice mortar rounds, non-priority artillery ammunition, spare clothing and several containers of replacement berets. An officer, upon returning from Arnhem, filed a report urging that berets not be dispatched in future re-supply drops; "...the effect on the morale of a hungry man, or one without ammunition, finding a container of berets instead of what he anticipates, has to be seen to be believed."
Since the formation of the Oosterbeek Perimeter, the 1st Airborne had accumulated an enormous quantity of wounded, both British and German, and by the morning of Sunday 24th September, the medical staff had approximately one thousand two hundred men in their care. The Division had been unfortunate in losing much of its medical facilities during the first days of the Battle. Only five of the fourteen Regimental Aid Posts, to which wounded men were initially sent for First Aid, remained intact, and although two of the three Main Dressing Stations, established by the Field Ambulances to provide care for the more serious cases, were in operation, many of their surgeons and orderlies had been captured on Wednesday 20th, whilst the Perimeter was still taking shape. Medical supplies were woefully short, bandages had to be improvised with cloth, and in many cases the application of such dressings was all that could be done for the wounded. The medical staff that remained worked ceaselessly and did everything in their power to ease their suffering, whilst unarmed stretcher-bearers continuously ran back and forth across the battlefield, dodging artillery fire and praying that the German snipers would allow them to go about their work unimpeded.
All available shelter for the wounded had long since been taken up. All the Main Dressing Stations and Regimental Aid Posts were filled to capacity, and thereafter the men awaiting treatment sat in the open, outside these buildings, whilst the shelling continued. The battalions comprising the Lonsdale Force had all lost their Regimental Aid Posts and so they relied on the medics of the 1st Airlanding Light Regiment, who had established their RAP just behind Oosterbeek Church, in and around the home of Kate ter Horst. She opened up her home and filled it to capacity with as many of the wounded and dying as she could. Throughout the battle she did all that any one person could do to make her guests comfortable and to ease their suffering.
On Sunday 24th, Colonel Graeme Warrack, the 1st Airborne Division's senior medical officer, obtained permission to arrange a truce with the Germans, generously complied with by Obergruppenführer Bittrich, commander of the II SS Panzer Korps, in order to evacuate as many of the wounded as possible into German care, where, although they would become prisoners of war, they would at least be sure of appropriate medical attention. German vehicles entered the Perimeter during the truce and removed approximately two hundred and fifty stretcher-bound men, whilst a further two hundred walking wounded were marched to the St Elizabeth Hospital.