The Molotov-Ribbentrop agreement did not last long because less than 2 years later on the 22nd June 1941 Hitler invaded Russia as part of Operation Barbarossa, attacking the soviet military positions held there and thus annulling any peaceful relations that existed with Russia.
According to legend, Stalin had a nervous breakdown when he discovered his former ally had turned against him.
Later, on another page we will discuss General Anders Army whose formation was the direct result of this hostility from Germany towards Russia. In essence though, the reason many Polish soldiers ended up displaced and living in foreign lands was directly attributable to Hitlers attack on Russia in Operation Barbarossa, the polish troops joining Anders army and thus ending up displaced all over the world.
The irony is that Hitlers attack on Russia led, ultimately, to freedom for many poles in captivity within the USSR at exactly the same time as Hitler was busy extinguishing Polish lives in concentration camps.
The UK During Operation Barbarossa
During Operation Barbarossa London was hosting many allied governments who had temporarily located to London for safety. Of these was the "Polish Government In Exile".
At this time, from a military viewpoint, Britain was exposed. There were few troops left in Britain to defend it, the Royal navy was out hunting German u-boats and the bomber aircraft did not have the capability to strike a blow into the heart of Germany.
Winston Churchill knew he had to get allies to help him in his fight against Hitler. He admired the Polish airmen after their performance in the Battle Of Britain and he also had massive respect for General Sikorski. Even if there was to be a British-Polish alliance it would not be able to deliver the needed strike against Germany due to lack of resources.
So Churchill decided he would try to make an ally out of Russia even though he despised Bolshevism.
He realised that Britain had the money and Russia the military might so on 12th July 1941 Molotov signed an agreement with Britain that led to the "Anglo-Soviet Treaty Of Mutual Assistance" whereby the 2 world powers would unite against Germany and fight for peace.
Britain had a great friendship with Poland during world war 2 and as discussed above Churchill was working up an ally in Russia.
This became a tricky predicament because Poland viewed Russia as its aggressor (and had just been invaded by them and their country wiped off the map).
Yet, to beat Germany the 3 countries, Britain, Poland and Russia would have to form a coalition and unite against Germany.
Therefore, General Sikoski, representing Poland, began talks with Ivan Maisky, The Ambassador To London.
The Sikorski-Maisky Agreement
The Sikorski-Mayski agreement was signed on 30 July 1941.
One of the things in this agreement was that Russia would release the Polish Deportees In Exile. A Polish army would be formed and all Polish citizens within Russia could apply to be in this army that would help Russia fight the Germans.
Unfortunately, the wording of this document, allegedly a typo by a Polish translator (No doubt a Russian working for Stalin!), was yet another slur to the Polish people. It referred to them getting an "amnesty" (implication of wrongdoing) as opposed to "release".
Nonetheless, this important agreement lead directly to General Anders being freed from a Russian Prison and forming Anders Army that would lead to many poles escaping Russia.
So really, it was Operation Barbarossa (the German invasion of Russia) that caused the Poles release from captivity, had the Germans not invaded Russia then it is not likely the Poles would have been released.
However, there was to be a backlash form this agreement as well. Whilst it opened diplomatic channels with Russia and was Churchills hope that it could be used to ask Russia where a large jumber of missing polish officers were (Katyn massacre), it was this issue in itself that would result in Russia later closing its borders in 1942, thus trapping a large number of poles in the Soviet Union for life.