75 years ago today: the start of World War II (w/archive photos)

Today marks the 75th anniversary of Germany's invasion of Poland, on Sept. 1, 1939, thus beginning the start of World War II. By the end of the war in 1945, more than 50 million, and by some count millions more, soldiers and civilians had died. The atrocities of the Holocaust stand sorely at the center of the tragedy of the war.

Some sites to peruse:

The History Channel offers a wealth of archival films, some in color, as well as other resources.

Life offers remarkable archival color photos of the invasion of Poland.

The U.S. Holocaust Memorial Museum offers extensive documents of the German invasion of Poland. The museum is a top resource globally for facts and background on the atrocities of the Holocaust and it also documents the stories of survivors.

The National World War II Museum in New Orleans offers many resources, including tips on gathering oral histories.