July 21, 1403 - Henry IV defeats rebels lead by Henry Percy (Hotspur) at the Battle of Shrewsbury.
July 21, 1831 – Leopold of Saxe-Coburg-Gotha, uncle of Queen Victoria and Prince Albert, becomes King of the Belgians. He was instrumental in bringing Victoria and Albert together.
July 21, 1861 - The first major battle of the Civil War, the First Battle of Bull Run, begins and ends with a Confederate victory.
July 21 - 1944 -Claus von Stauffenburg and fellow conspirators are executed in Berlin for the plot to kill Hitler.