12. the invasion of poland by led to france and britain declaring war on the aggressor nation. this is commonly considered the official start of world war ii.

The correct answer is Germany.

On Sept. 1, 1939, Germany invaded Poland.

This is seen as the start of World War II.

Germany

Explanation:

The German invasion of Poland was a military action of Nazi Germany aimed at annexing the Polish territory. The technical operation, known as "White Case" (in German, Fall Weiss), began on September 1, 1939 and the last units of the Polish army surrendered on October 6 of that same year. It was the trigger of the Second World War in Europe and ended with the Second Polish Republic.

john maynard keynes developed new economic theories in response to the stock market crash of 1929. great depression of the 1930s. first and second world wars. economic boom of the 1950s.

sitting in that one chair where he could get shot at was his worst decision.