May 12, 1191 - Richard I married Berengaria of Navarre.
May 12, 1264 - The Battle of Lewes between Henry III and the Earl of Leicester, Simon de Montfort, begins.
May 12, 1536 - Sir Francis Weston, Mark Smeaton, William Brereton, and Henry Norris, all alleged lovers of Anne Boleyn, were tried for and convicted of treason. Only Smeaton confessed to the charges. George Boleyn was tried for the same crimes a few days later.