How come Louis XVI was Capet?
Louis XVI was the king of France upon the outbreak of the French Revolution and was arrested and summarily executed by the revolutionaries as a symbol of the death of the monarchy. Louis was a member of the Capet family, which had held power in France in one form or another since the early medieval period.
By renaming Louis XVI Louis Capet, it symbolized him becoming a regular citizen of the French Republic rather than a monarch. This made it legally more acceptable to execute the king and symbolized the dissolution of his official position within French society.