Well, I would suggest that when thousands [or millions] of individuals recognize a cause that is valuable to them personally and join with other thousands or millions of individuals, great things can happen. But it all starts with the individual.
In either case, being ordered into a duty against one's self interest is entirely antithetical to Rand's highest moral purpose which is the achievment of one's own happiness.
Wow. You really do have a warped impression of her philosophy. If a man desires liberty but must go to war to defend it or regain it, then the fact of being put in harm's way is not against his self interest.
Really, your understanding of Rand is inaccurate and, actually, pretty insulting.
And in a Randian Army a few of them are going to have to be generals and colonels and order, force, compel the privates into situations directly contradictory to their self-interest. Rand is very clear about her thoughts regarding the notion of a "common good," and yet no nation or community without such a concept will be able to effectively defend itself when tested.
"If a man desires liberty but must go to war to defend it or regain it, then the fact of being put in harm's way is not against his self interest."
That would be well and good if men fought wars by and for themselves. They are very well free to do so, but they sure won't win them that way. Even the buck private who goes to war for liberty must be willing to surrender his if he is to be part of a greater unit that carries the fight to an enemy. At some point, the choice as to whether or not to risk his life is taken away from him, and you have what Randians refer to as compulsory sacrifice or forced altruism. Now, that individual can make the choice to not join the military, which if enough folks decide likewise, leads the society undefended...unless of course you conscript people and we know the liberterian view on that.
Really? Let's take a look at Rand's own words and how they would apply in a military context:
"Only on the basis of individual rights can any good—private or public—be defined and achieved."
I would call the defense of a nation a public good. Can we agree on that? Yet, by virtue of it's being, no military that does not suspend or at least modify the individual rights of its servicemembers will be able to maintain the order and discipline necessary to perform its mission. Subordinates must follow orders of their superiors, even if it is in direct hazard to that subordinate's personal interests (and often life).
"Only when each man is free to exist for his own sake—neither sacrificing others to himself nor being sacrificed to others—only then is every man free to work for the greatest good he can achieve for himself by his own choice and by his own effort."
A military leader must frequently place his mission above the the good of his individual soldiers. That's just the way it is.
"And the sum total of such individual efforts is the only kind of general, social good possible."
Nope. Sometimes the sum total of a collective effort is greater than it's individual parts. My understanding of Rand may be, "inaccurate and, actually, pretty insulting," but I would contend that Rand's understanding of reality is much the same.