The "well regulated militia" language of the Second Amendment, which has confused so many for so long, is relatively easy to trace back to its earliest American author and bill of rights usage. Here is why. Congress based the first clause of the Second Amendment on an exact quote taken from the 1776 Virginia Declaration of Rights. [The Origin of the Second Amendment, p.748] Virginia's Second Amendment related language was America's first in a state constitutional level document. So what exactly was the language Congress relied upon?
"that a well-regulated militia, composed of the body of the people trained to arms, is the proper, natural, and safe defence of a free state;" [OSA, p.459]
Why was this language relied on by Congress as an amendment to the Constitution? The ratifying conventions of Virginia and North Carolina adopted proposed bills of rights quoting Virginia's earlier bill of rights language. [OSA, pp.459, 505] New York's convention included virtually identical language, which itself had been based on Virginia's language. New York described a well regulated militia as "including the body of the people capable of bearing arms". [OSA, p.481] It is clear that these bill of rights "well regulated militia" references related to the body of the people, not to a government formed select militia like the modern National Guard as has so often been claimed by proponents of gun control.
So who wrote this original language back in 1776? George Mason, [The Founders' View of the Right to Bear Arms, p.62] and he used virtually the same language prior to the beginning of the Revolutionary War to describe a voluntary defensive association in Fairfax County, Virginia. It was formed so the people could protect their rights and the existing constitution from violation by government officials and the military forces raised by them. The language that the Second Amendment was directly based upon was intended to protect against unconstitutional and rights violating actions of government carried out by force.
There is extensive historical evidence that "well regulated militia" did not refer to a government regulated or authorized militia, but rather to locally organized defensive forces. Mason's early 1775 well regulated militia references applied to self-embodying, self-organizing, self-officering, self-training, and self-arming associations of all the free men for local defense against a current danger - British government officials and forces. [FVRBA, pp.45-50] No such local defensive associations could have existed unless the men possessed and knew how to use their own arms. The historical sources indicate that government officials and forces were taking every measure possible to limit the ability of Americans for self-defense by decreasing the availability of arms and ammunition. [FVRBA, pp.36-43]
This historical information makes the Second Amendment's language and meaning much more clear. Claims of ambiguity about the Second Amendment evaporate once the stated meaning of its terms and the historical background of their use are known. We find that what advocates of gun control have always said about the Second Amendment's intent, that it was not intended to protect individual rights, is diametrically opposed to reality and extensive period historical evidence. Individuals voluntarily associated for defense against unconstitutional and rights violating actions of force by the government in 1774 and 1775 prior to the formation of any new American governments or any hostilities of the Revolution. This activity was based upon fundamental, unalienable rights that Americans subsequently protected against government violation in their state and federal bills of rights.
For further and much more detailed information about the Second Amendment's development and purpose, read The American Revolutionary Era Origin of the Second Amendment's Clauses, my short, documented online history.