Back in the day of militias and Napoleon-esque armies, there really was not that much of a difference between a professional soldier and a militiaman. A militiaman could be drilled and trained to fight standing in a line with a musket in a few weeks. So militias were still pretty effective against regular armies. Not as good, but pretty decent.
Exactly, and that is why guns made men equal.
Prior to firearms it took years of disciplined training to master the martials arts of the Knights. They started training as young boys which continued into thier 20s on various moves, counters to moves, many different weapons etc. In fantasy a lot is heavily simplified for our enjoyment, but the education and training behind real fighting Knights/Samurai or whatever they were called in the local society was intense. They became the equal of blackbelts in several martial arts and with several different fighting styles and weapons.
Contrast that with the average peasant, who spent most waking hours in labor toiling. Even if they wanted to rise up or got ahold of the weapons of the day they were absolutely no match for thier rulers enforcers who dedicated thier lives to combat training.
When guns, and to a lesser extent powerful crossbows before them came onto the scene it changed the balance. That is why crossbows were outlawed in many places even before guns became common. A longbowman took years of training to perfect thier art, but anyone could pick up a crossbow and shoot a heavy bolt through the armor of a highly skilled knight that took over a decade of training to create.
With firearms commonplace suddenly an average person with a few weeks or months training was a match for a Knight. That meant training Knights for years was no longer effecient, cost effective etc and that thier worth was much less.
Conscripted armies became the norm, as in the times of Napoleon which you reference.
Men were more or less equal, though some with more training had an advantage it was not an advantage that tooks years of training to overcome.
Militaries now have advanced considerably and are once again bringing people back into the times of Knights. When operation and ownership of the most formidable weapons are specialties, and held primarily by governments and a ruling class.
So while you may hear statements like the six shooter made all men equal, the atom bomb and jet fighter once again made them peasants. Peasants with a vote for red or blue, but still peasants.
Yep, today if America didn't have a standing army, we'd be ruled by China.
A capable modern standing army is certainly a necessary evil today.
But that is the purpose for which arms are protected under the Constitution
I dissagree, I feel guns are a right themselves.
Granted, but that is not why they are protected by the constitution. That was considered a basic thing at the time not even necessary to state. The ability to retain defense against a ruler was a radical perspective, as radical as it was in the Magna Carta, and that was necessary for them to state as it was not a right that existed in most of the world (defense against common criminals was normal in the world at the time). So that is why arms were protected as something the government could not regulate and infringe on.
So even if it is not the reason most of us defend that right, it is why that right was included in the Bill of Rights.