I find it hard to believe the the 2nd Amendment is exclusively for national defense

[Nuclear Unicorn]

14. I would buttress your argument with the observation

A militia would certainly augment a conventional force but it would also offset that conventional force. I read the Federalist Papers not long ago and one of the contentions with the anti-Federalists revolved around the distrust of standing armies.

The purpose of the militia is "the security of a free state." Free from whom? Exclusively foreign invaders? Judging from the balance of the BoR there are hard limitations placed on the government even in the course of its proper duties of maintaining civil order and defending itself from threats. The singular preoccupation of the Bill of Rights is to paint brightly those lines the government cannot cross in the commission of those duties so as to preserve more freedom for the people than power for the government.