Final answer:
The execution of King Louis XVI marked the radical phase of the French Revolution, with significant debate about whether it exemplified necessary justice or excessive violence. His execution challenged the idea of a constitutional monarchy and sparked international controversy over the revolution's direction.
Step-by-step explanation:
The execution of King Louis XVI during the French Revolution was a significant turning point, leading to widespread debate about the principles of the revolution itself. Some argue that his execution was unjust because it represented a descent into popular anarchy, as highlighted by Federalist criticism in the United States. They believed that the revolt had gone too far, transitioning from a legitimate revolution to unnecessary violence and ridding France of the constitutional monarchy that at one point seemed like a step towards more democratic governance. Louis XVI's escape attempt and perceived indifference to the economic hardships faced by the populace added to his unpopularity, but the question remains whether his execution served justice or descended into mob rule.
Marie Antoinette's execution followed in October of 1793, further cementing the revolutionaries' break from monarchical rule and thus altering the political landscape of Europe. This period, known as the Reign of Terror, brought into sharp relief the complexities and extremities of revolutionary zeal. It was a time when supporters of the monarchy and constitutional rule could easily become targets, as evidenced by the arrest and narrow escape of figures like Thomas Paine, who opposed the execution of the monarchy despite supporting revolutionary ideals.