The founders idea of the militias was all citizens would be serving part time in militias bearing arms in lieu of professional standing armies . Of course, the common folk would have to be guaranteed the right to bear arms or there would be no militias; thus we have the 2nd amendment. Yes, I know that makes no sense today just like the second amendment. The founders as well as most colonist feared a professional standing army. They saw militias as the answer. Cost was low, they could be integrated into a national army if needed, and once the hostilities ended, they could be sent back home saving a ton a money. The stumbling block was much of the gentry and businessmen feared that the uprisings in Europe might spread to the US if the public had free access to arms as they did at that time. So in order to protect the militias, the congress acted to make sure that there would be no infringement to the right to bear arms insuring that militias could be formed. I think it was a good idea in it's day but it just didn't work. Military science and weaponry in 19th century became far more sophisticated, well beyond the capabilities of part time volunteers.