Final answer:
The lack of support from France and Great Britain, along with the Soviet Union's invasion, weakened Poland during World War II.
Step-by-step explanation:
Another factor that weakened Poland was the lack of support from France and Great Britain during World War II. Even though they declared war on Germany, they did not provide significant assistance to Poland. Additionally, the Soviet Union, under a secret provision of the Nazi-Soviet Pact, invaded Poland from the east, further weakening the country.