During the planning for Operation Market Garden, Sosabowski expressed serious concerns regarding the feasibility of the mission.
 Among Sosabowski's concerns were the poorly conceived drop zones at Arnhem, the long distances between the landing zones and Arnhem Bridge and that the area would contain a greater German presence than British intelligence believed.
 Despite Sosabowski's concerns and warnings from the Dutch Resistance that two SS Panzer Division were in the operations area, Market Garden proceeded as planned.

The Polish 1st Independent Parachute Brigade was among the Allied forces taking part in Market Garden.
Due to a shortage of transport aircraft, the brigade was split into several parts before being dropped into the battle.
A small part of the brigade with Sosabowski was parachuted near Driel on 19 September, but the rest of the brigade arrived only on 21 September at the distant town of Grave, falling directly on the waiting guns of the Germans camped in the area.
The brigade's artillery was dropped with the British 1st Airborne Division, commanded by Major-General Roy Urquhart, while the howitzers were to arrive by sea, which prevented the brigade from being deployed effectively.
Three times Sosabowski attempted to cross the Rhine to come to the assistance of the surrounded 1st Airborne Division.
Unfortunately, the ferry they hoped to use had been sunk and the Poles attempting to cross the river in small rubber boats came under heavy fire.
Even so, at least 200 men made it across the river and reinforced the embattled British paratroopers.

Despite the difficult situation, at a staff meeting on 24 September, Sosabowski suggested that the battle could still be won.
He proposed that the combined forces of XXX Corps, under Lieutenant-General Brian Horrocks, and the 1st Polish Parachute Brigade should start an all-out assault on the German positions and try to break through the Rhine.
This plan was not accepted, and during the last phase of the battle, on 25 and 26 September, Sosabowski led his men southwards, shielding the retreat of the remnants of the 1st Airborne Division.
Casualties among the Polish units were high, approaching 40%, and were at least in part, the result of Lieutenant-General Browning's decision to drop the paratroops 7 kilometres from the bridge at Arnhem.

After the battle, on 5 October 1944, Sosabowski received a letter from Field Marshal Bernard Montgomery, commander of the Anglo-Canadian 21st Army Group, describing the Polish soldiers as having fought bravely and offering awards to ten of his soldiers.
However, on 14 October 1944, Montgomery wrote another letter, this time to the British commanders, in which he scapegoated Sosabowski for the failure of Market Garden.
Sosabowski was accused of criticizing Montgomery, and the Polish General Staff was forced to remove him as the commanding officer of his brigade on 27 December 1944.

At the Moscow Conference in October 1944, a turning point came in Anglo-Polish relations.
On Prime Minister Churchill’s request, the Polish delegation arrived in Moscow on 12 October 1944.
Upon arrival, Churchill told them to be present at the discussions between himself, Joseph Stalin and the Communist Polish Lublin Committee.
Consequently, Churchill coerced Polish Prime Minister Stanisław Mikołajczyk into cooperating with Stalin’s disciples, or else risk losing Britain’s support for the remainder of the war.
From the British perspective, any news that could be beneficial to their coercion tactics would be welcome.
The information came on 16 October in a telegram to Field Marshal Sir Alan Brooke, the Chief of the Imperial General Staff, who was present in Moscow as Churchill’s military advisor.

The message stated that Sosabowski’s brigade performed badly.
Churchill could use this claim to put more pressure on Mikołajczyk to cooperate, because it could be argued that one of his most valuable assets, Sosabowski’s elite brigade, was no longer useful to the Allied war effort.
Montgomery’s telegram is exceptional to his behavior in that timeframe.
Two days prior
During the planning for Operation Market Garden, Sosabowski expressed serious concerns regarding the feasibility of the mission.  Among Sosabowski's concerns were the poorly conceived drop zones at Arnhem, the long distances between the landing zones and Arnhem Bridge and that the area would contain a greater German presence than British intelligence believed.  Despite Sosabowski's concerns and warnings from the Dutch Resistance that two SS Panzer Division were in the operations area, Market Garden proceeded as planned.
The Polish 1st Independent Parachute Brigade was among the Allied forces taking part in Market Garden. Due to a shortage of transport aircraft, the brigade was split into several parts before being dropped into the battle. A small part of the brigade with Sosabowski was parachuted near Driel on 19 September, but the rest of the brigade arrived only on 21 September at the distant town of Grave, falling directly on the waiting guns of the Germans camped in the area. The brigade's artillery was dropped with the British 1st Airborne Division, commanded by Major-General Roy Urquhart, while the howitzers were to arrive by sea, which prevented the brigade from being deployed effectively. Three times Sosabowski attempted to cross the Rhine to come to the assistance of the surrounded 1st Airborne Division. Unfortunately, the ferry they hoped to use had been sunk and the Poles attempting to cross the river in small rubber boats came under heavy fire. Even so, at least 200 men made it across the river and reinforced the embattled British paratroopers.
Despite the difficult situation, at a staff meeting on 24 September, Sosabowski suggested that the battle could still be won. He proposed that the combined forces of XXX Corps, under Lieutenant-General Brian Horrocks, and the 1st Polish Parachute Brigade should start an all-out assault on the German positions and try to break through the Rhine. This plan was not accepted, and during the last phase of the battle, on 25 and 26 September, Sosabowski led his men southwards, shielding the retreat of the remnants of the 1st Airborne Division. Casualties among the Polish units were high, approaching 40%, and were at least in part, the result of Lieutenant-General Browning's decision to drop the paratroops 7 kilometres from the bridge at Arnhem.
After the battle, on 5 October 1944, Sosabowski received a letter from Field Marshal Bernard Montgomery, commander of the Anglo-Canadian 21st Army Group, describing the Polish soldiers as having fought bravely and offering awards to ten of his soldiers. However, on 14 October 1944, Montgomery wrote another letter, this time to the British commanders, in which he scapegoated Sosabowski for the failure of Market Garden. Sosabowski was accused of criticizing Montgomery, and the Polish General Staff was forced to remove him as the commanding officer of his brigade on 27 December 1944.
At the Moscow Conference in October 1944, a turning point came in Anglo-Polish relations. On Prime Minister Churchill’s request, the Polish delegation arrived in Moscow on 12 October 1944. Upon arrival, Churchill told them to be present at the discussions between himself, Joseph Stalin and the Communist Polish Lublin Committee. Consequently, Churchill coerced Polish Prime Minister Stanisław Mikołajczyk into cooperating with Stalin’s disciples, or else risk losing Britain’s support for the remainder of the war. From the British perspective, any news that could be beneficial to their coercion tactics would be welcome. The information came on 16 October in a telegram to Field Marshal Sir Alan Brooke, the Chief of the Imperial General Staff, who was present in Moscow as Churchill’s military advisor.
The message stated that Sosabowski’s brigade performed badly. Churchill could use this claim to put more pressure on Mikołajczyk to cooperate, because it could be argued that one of his most valuable assets, Sosabowski’s elite brigade, was no longer useful to the Allied war effort. Montgomery’s telegram is exceptional to his behavior in that timeframe. Two days prior 
Stanisław Sosabowski