Poland was conquered by USSR against their will (well. More like betrayed by British and given to USSR)
Betrayed or at least with their blessing. The Curzon Line, which was the Entente plan after WW1, was reaffirmed before and after the German invasion. The territory Poland annexed in 1921 was effectively 'returned' to the USSR.
The twelfth cocktail by lunch and everything was a fight on the beaches for Churchill.