World War II

AUDIO:[voice of Adolph Hitler...]
75 years ago today, Adolph Hitler was trying to explain to the world why Germany had invaded Poland just the day before.
ANNOUNCER: Poland, for the first time this evening, has shot at regular soldiers upon our territory....voice of Hitler...From now on, bomb will be met by bomb!
And it was. The following day, Britain and France declared war on Germany, marking the start of World War II.
It was a war in which science and technology would play crucial roles. Sonar and radar made it easier to detect enemy submarines and airplanes. Advances in aeronautics provided airplanes that could fly farther, higher, and faster. Analog computers helped decipher enemy codes. And working under some of the tightest security in history, nuclear physicists produced the weapon that eventually brought the war to an end: the atom bomb.
And after the war, many of those inventions quickened the pace of scientific discovery. Sonar helped scientists begin to map the ocean floor.