Operation Market (the codename for the airborne phase of the plan, Garden being that of the ground forces) involved a high degree of risk for all of the units involved. The danger was particularly severe for the 1st Airborne Division, landing at Arnhem, sixty-four miles into German territory, because their fate largely depended upon the success of others. If their American cousins, landing to the south, failed to capture any one of their major bridges, then all of the estimated eleven thousand nine hundred men of the 1st Airborne Division and its attached units would likely be cut off from friendly forces and inevitably captured. Even an unusually long delay in the arrival of the relieving ground forces could result in the same fate, because, although airborne troops are exceptionally well trained, they lack the basic support weapons of an ordinary infantry unit, such as tanks and heavy artillery, and so cannot be expected to survive long in isolation against an enemy plentifully equipped with these.
Any operation involving the dropping of lightly armed troops behind enemy lines is, by definition, a risky venture, yet the basic proposal of Operation Market Garden seemed quite reasonable, if a little ambitious. German opposition in the immediate area of the landings was believed to be minimal, and as Arnhem was far behind the front line it was predicted that the local garrison would consist of approximately one hundred and fifty men of the Home Guard variety, largely consisting of First World War veterans and Hitler Youth; nothing of concern to an elite airborne division.
Despite this, a number of factors arose which placed the outcome of the Operation in jeopardy. Some of these came about through unfortunate circumstances, but most were a direct result of the over-optimistic view that the Germans were already beaten. The Allies knew that Army Group B had reformed and established a strong front line, but the general feeling was that it would only require another firm blow to send them reeling in all directions again. This was a very dangerous assumption, as those that had experience of fighting the Germans knew that they were excellent soldiers and could fight viciously even when the situation was hopeless.
One of the main complicating factors was the short time available for planning the Operation. Most airborne raids were developed over a period of months; the Normandy landings had three and a half months of planning behind it, at Divisional level, and it involved only half of the thirty-five thousand troops that were to participate in Market Garden. The Operation was announced on the 10th September and was to be launched on Sunday 17th September, leaving the three airborne divisions just seven days to plan their battle.
The report that Arnhem was free of serious resistance was incorrect. Several days before the Operation was to be launched, the 9th and 10th S.S. Panzer Divisions were moved into the Arnhem area to rest and refit, with some units in the town and others up to thirty miles to the north and east. The expected full operational strength of each of these divisions would have been approximately twenty thousand men, however they had both been so severely mauled during the Normandy fighting that they now mustered a combined force of approximately six thousand men. Although numerically weaker to the 1st Airborne Division, they possessed a range of tanks, self-propelled guns, other armoured vehicles and artillery pieces, and their men were all excellently trained and battle-hardened.
These two Divisions were just the immediate resistance that would confront the 1st Airborne Division; within several days other, more heavily equipped units could be expected to arrive on the scene. Equally by chance, Feldmarschall Walther Model, the Commander of Army Group B, had recently placed his headquarters in the Tafelberg Hotel in Oosterbeek, a village just over four miles from Arnhem, and very close to one of 1st Airborne Division's drop zones. Model possessed brilliant skills of improvisation when faced with a crisis, and his presence on the battlefield was to result in the German reaction to Market Garden being quicker, better organised and reinforced than would otherwise have been expected.
The British were aware of the presence of the two Divisions, but little word of it filtered through to the 1st Airborne. The primary source of the intelligence was Ultra, the codename for the interception and decoding of German signals received through the Enigma machine. Ultra clearly identified the presence of the 9th and 10th S.S. Panzer Divisions, but due to the vital need to protect the system and not give the Germans cause to suspect that their codes had been broken, only a select few were privy to this information in its purest form. The 1st British Airborne Corps, under whose umbrella all the airborne units involved in Market Garden were to fight, only received a particularly vague suggestion of armoured strength in the area. The commander of the Corps, Lieutenant-General Browning, accordingly advised Major-General Roy Urquhart that the immediate opposition to his 1st Airborne Division would be derisory, but that they could later expect to encounter little more than a Brigade Group of infantry supported by a few tanks.
More compelling evidence was to come, first from the Dutch Underground. Their organisation was not so well administered and equipped as the resistance groups of other countries, and the British had further reason to mistrust their reports, due to their experience of betrayal earlier in the War which had resulted in fifty Allied agents parachuting into waiting German arms. Some of the reports were not accurate, but others did indicate a sudden and concentrated presence of enemy armour in the Arnhem area. The only confirmation that the 1st British Airborne Corps received of this was from aerial reconnaissance photographs requested by their Intelligence Officer, Major Brian Urquhart (no relation to Major-General Roy Urquhart). These showed a small number of tanks close to one of the 1st Airborne Division's drop zones, but a mere handful of armoured vehicles did not automatically mean the presence of an entire panzer division. Lieutenant-General Browning chose to play down the significance of these photographs, and when Major Urquhart persisted with his opposition to the plan, Browning forced him away on a period of sick leave.
Only one other man lodged serious objection to Operation Market Garden, and he was Major-General Stanislaw Sosabowski, the commander of the Polish Parachute Brigade, who would be accompanying the 1st Airborne to Arnhem. He was a hugely experienced officer in possession of a fine military mind, and his objection to Operation Comet, the original version of the Market Garden plan which involved just the 1st Airborne Division and Polish Brigade, contributed greatly to its justified cancellation. Sosabowski, however, was no diplomat, and he was becoming increasingly isolated from his fellow commanders due to earning himself a reputation of objecting to absolutely everything. He later admitted that his condemnation of Market Garden was not as strong as it might have been because he was aware of how both he and his opinions had come to be regarded.