An aspect of this whole debate over military enlistment contracts that is rarely discussed, even among libertarians who consider the freedom of contract to be nearly sacred, is why such contracts, or indeed a standing military, are necessary in the first place for effective "national defense." (Yes, I know, the libertarian readers of this blog all know the answer to this, but it bears repeating for the newly liberty-conscious or uninitiated). When the thirteen sovereign states first declared their independence from Great Britain, the citizen militias that formed to drive the British out were NOT regular standing armies in the tradition European mold, but citizen militias. Their members signed no enlistment contracts, were not bound by any formal oath of service, and were not under the "command" of any formally commissioned officers. Indeed, they functioned very much like the 4GW forces Amerika has faced in every armed conflict it has embroiled itself in since the end of World War II. Only after the Continental Congress appointed George Washington supreme commander of the newly-formed Continental Army (and by what authority did they do this, one might ask?) did the rudiments of a formal army emerge, an event that foreshadowed the metastasis of the standing army that the founders (allegedly) tried to guard against and that we are burdened with today. (The late great libertarian sage Murray Rothbard wrote a fascinating description of the real George Washington, one certainly not taught in the Establishment's public indoctrination centers called public schools and state universities. His account details, among other unsavory things, Washington's ambitious campaign to turn the Continental Army into a carbon copy of the standing imperial armies then prevalent on the Old Continent).
Up until roughly 1779, the nature of the Continental Army was that of a loose collection of local militias, fluid in structure and composed entirely of volunteers, unbound by any form of formal contract. And why would they need one? These were men (and not a few women) committed to fighting for THEIR OWN FREEDOM, a commitment of the heart and soul that certainly does not require the organization of an oppressive gang or conscription thereinto. It was only after Washington and various allies in the Continental Congress succeeded in "Prussifying" the Continental Army, which after independence became the United States Army, that the rigid structures of imperial nationalist armies took hold, with all of the attendant corruption and abuse of power and authority. In other words, the federal Army was no longer, for all practical purposes, a volunteer citizens militia, but a formal institution of the central government, a recipe for creeping tyranny under any set of circumstances.
To summarize, neither an enlistment contract nor a standing army is in any way necessary for TRUE "national defense" if the government under which a nation's people live is one that respects and protects their lives, liberty, and property in accordance with constitutional and natural law, thus making it a nation worth defending in the first place.. Free people will not hesitate for a second to arm themselves and rush to their nation's defense when they know that it is genuinely and tangibly threatened. They certainly don't need any government to tell them this or force them into doing so when their homes, properties, families, and communities are under direct threat of assault, for it is mankind's natural instinct to protect that which he loves and in which he has a natural stake of ownership.
A standing army, on the other hand, is nothing but the State's armed muscle, a tyrannical force used to impose the State's will upon its subjects for its own narrow and selfish purposes, purposes that seldom ever have anything to do with the defense of the citizen's home, property, rights, life, and community. For this reason a legal ruse is required, backed by subterfuge and coercion, to mask the deceit and criminality behind the army's mission. True patriots, deceived into believing that their service in such body is an act of genuine lawful good, must be forced into a state of involuntary servitude to this monstrous organization once they discover the organization's real purpose: to serve the ends of the State at the citizen-patriot's expense. The enlistment contract is the instrument through which this is accomplished, and is thus a pseudo-legal perversion, a weapon of fraud and subversion of law, rather than a legal guarantor of institutional integrity or individual freedom of contract.
(*the misrepresentation being that the mark is enlisting to "defend the nation/Constitution/freedom)
(** The State's fiat declaring military enlistment contracts as exceptions to common law notwithstanding, any contract in which one party is allowed to violate or abrogate the contract at will is NOT a valid, legally binding contract)