Josef Stalin, dictator of the Soviet Union, declares war against Poland.
NOTE: Although the United Kingdom and the Republic of France had declared war on Germany for its invasion of Poland, neither nation declared war on the U.S.S.R. for its invasion of Poland.
[restored 7/23/2022] Thanks to Jim Lorenz for this entry.
Subsequent Events:
References:
Why Germans Supported Hitler, Part 1.
www.fff.org/freedom/fd0703a.asp