A combined American and French army supported by A heavily armed French fleet.
Louis XVI was an autocrat that ruled France. His is mostly known for his relation to Louis XIV of France, who was the ruler in power when the French Revolution began.
Madison understood that power can corrupt as seen with the kings of their time. So Madison set up the form of government that relies on separate branches of government that operates under checks and balances. This means that no one branch can get too powerful and overrule the other branches. We see this in modern government in the legislative, executive and judicial branches. Madison improved upon the idea that power cannot be held by one man or a few people.