Excellent animated visualization of day-to-day changes in the European theater of World War II

For WW II:

This video shows the changing front lines of the European Theater of World War II every day from the German invasion of Poland to the surrender of Germany.

Here's WW I:

See the changing front lines of World War I in Europe and the Middle East from the first declaration of war by Austria-Hungary on July 28, 1914 up to the German armistice on November 11, 1918. Each slide represents 5 days.

These are by Youtube user EmperorTigerstar, and he has several additional map animations available.