I don't know why you think that I need to look up the definition of militia. But the link that I provided provides a rather lengthy explanation of what militia

I don't know why you think that I need to look up the definition of militia. But the link that I provided provides a rather lengthy explanation of what militias are and the different forms of militias that existed in the USA from colonial times until the passing of the 2nd amendment. It certainly is much more informative than "a military force that is raised from the civil population to supplement a regular army in an emergency". Incidentally I failed to look up the actual law of the time. But the 1792 militia law included every "free able-bodied white male citizen" between the ages of 18 and 45. Which, in a world that only paid attention to white men, basically was "the people".