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.