Suspended and arrested during the Insurrection of 10 August 1792 , he was tried by the National Convention , found guilty of treason , and executed by guillotine on 21 January 1793 . Suspended and arrested as part of the insurrection of the 10th of August during the French Revolution , he was tried by the National Convention , found guilty of high treason , and executed by guillotine on 21 January 1793 as `` Citoyen Louis Capet '' .