The french and British guaranteed that if Poland was attacked they would help. Since france had a common border with Germany there was no excuse except for lack of resolve in not coming to Poland's aid. When the Soviets stabbed Poland in the back and attacked from the East, Poland was doomed. She could not fight Germany and Russia alone. Before the attack france kept hoping Poland would give in to German demands and made sure Poland would do nothing to "provoke" the Germans. That was one of the reasons for Polish unpreparedness. france was hoping that Poland would be another Czechoslovakia and avoid having to fight. Poland resistance to Hitler's demands put france into the position of having to declare war. But it was a declaration in name only. They did nothing until Germany attacked the West in 1940.