What battle marked the back stabbing break of the Non-Agression Pact by Germany?

The Battle of Stalingrad

Explanation:

It is famous for its line "Not one step back!" The Battle of Stalingrad (23 August 1942 - 2 February 1943) was a major battle on the Eastern Front of World War II in which Nazi Germany and its allies fought the Soviet Union for control of the city of Stalingrad in Southern Russia, on the eastern boundary of Europe.

the answer is 250 percent.

battle of survival between farmers and the rabbits during the great depression