Via Jerry Coyne,
1305, William Wallace (FREEEDOM!) was executed for high treason; and by “executed” I mean hanged until he was nearly dead, emasculated, disemboweled with his intestines burned in front of him while he was still alive, and then decapitated. People were cruel in those days.
Yes, they were. Upon the Restoration, Oliver Cromwell was disinterred and his head exhibited on a pike for 18 years. Beheading was a common subject of art for centuries.
http://nailheadtom.blogspot.com/2016/11/beheading.html
http://nailheadtom.blogspot.com/2017/06/beheading-update.html