It was in time of revolution. The revolutionaries cut his head: "REVOLUTIONARIES WAIT FOR MY HEAD ON A SILVER PLATE". And before that he had to go in exile "NOW IN THE MORNING I SLEEP ALONE, SWEEP THE STREETS I USE TO OWN..". He really held the key in his kingdom. He died guilty of treason that's why: "PEOPLE COULDN'T BELIEVE WHAT I BECOME".
Why they name the roman cavalry? Easy.: he tried to scape to belgium. That time was called holy roman empire. And he was recognized with A coin with his face, so the people who recognized him sent the roman cavalry for bust him. If you want to know more read his biography. Louis xvi of france. Nothing more to say.