The 1939 invasion of Poland caused Britain to declare war on Germany, which started WWII.
italy
Poland.
1939
Czechoslovakia
Great Britain and France declared war on Germany in 1939, because germany had invaded land that Great britain had to protect for france.
Great Britain and France declared war on Germany in 1939, because germany had invaded land that Great britain had to protect for france.
if you mean which country it was Poland
September 1939
France and Britain had promised to declare war if Germany tried to obtain anymore territory. And they kept that promise when Poland was invaded.
poland
Because at 1 September 1939 Germany invaded Poland.