Some notes:
Besides the advantage of being armed, which the Americans possess over the people of almost every other nation, the existence of subordinate governments, to which the people are attached, and by which the militia officers are appointed, forms a barrier against the enterprises of ambition, more insurmountable than any which a simple government of any form can admit of.
Commas. They’re a real bastard sometimes. The first part of the sentence, which says being armed has advantages, is independent from the point of the sentence, as is the second section. Think of it like the last sentence you just read. I could rewrite that without the subordinate section and it would still make sense: “ The first part of the sentence is independent from the point of the sentence, as is the second section.” The commas separate two thoughts that are not the same but are related. “Besides the advantage of being armed,” introduces that this sentence isn’t so much about the fact that anyone specific is armed, but something else. The next bit, “which the Americans possess over the people of almost every nation,” is an observation that, when this was written, lots of Americans were armed, but it is bookended with commas and written in passing and not as the main thrust of the sentence. The rest of the sentence is the main thought of the sentence: governments and militias for the barrier against “ambition”.
An example of how I might use this grammar in everyday life would be, “Besides the affordability of hamburgers, especially ones from McDonald’s, I love the taste combination of red meat, bacon, cheese, and ketchup.” The thoughts about the affordability of burgers, their existence at McDonald’s, and my love of them are related but separate, and we could do away with the bit about McDonald’s and the sentence would still make sense. From this sentence you can discern that burgers are cheap, McDonald’s has them, and I like them for other reasons. From the quote you cite, one can discern that being armed has advantages, lots of Americans are armed, and the state militia is the best bulwark against “ambition, etc.” If anything, this quote you chose suggests that the militia, attached to the states (“subordinate governments”) is the thing conferring the advantages Americans possess over every nation.
More importantly, this sentence mentions that people are armed as a fact, not an argument, but that the militia is the object it argues for as a bulwark against ambition. It’s referring to the armed militia, the group, not armed individuals, Not the best thing to focus on, for the point you’re trying to make, since it’s explicitly arguing something else — specifically, it’s arguing what I wrote in my article that you derided.
The Militia Act of 1903 established, “That the militia shall consist of every able-bodied male citizen of the respective States, Territories, and the District of Columbia, and every able-bodied male of foreign birth who has declared his intention to become a citizen, who is more than eighteen and less than forty-five years of age and shall be divided into two classes-the organized militia, to be known as the National Guard, Guard of the State, Territory, or District of Columbia, or by such other designations as may be given them by the laws of the respective States or Territories, and the remainder to be known as the Reserve Militia.”
The 1903 law has been modified a couple of times, mostly to do with the length of service and funding but the definitions have remained the same for 115 years.
National Defense Act of 1916 replaced the 1903 statute you reference. The 1903 law is no longer law, so long as the 1916 act remains in law.
We also have laws in New York that ban women showing skin above the ankle, which are likewise no longer laws, because other laws superseded them.
EDIT: I was a bit confused, thinking that the posting of the link to your piece as a response to mine was a post by the author of the comment on my article. I see you’re not the same person, so I’ll delete the relevant comment here.