Harrisonburg was (is) the site of Fort Beauregard, which was built to defend the Black/Tensas/Ouachita River system from invasion by Union gunboats during the Civil War. The activity at that site during the Civil War was intensive, and is way beyond the scope of anything that could be presented on this forum.
I am unfamiliar with the current condition of Fort Beauregard, so cannot speak to that. But as far as local/state/federal conservation efforts there are concerned, I can speak to that with a great deal of familiarity.
If you are expecting federal help in this area, you have to be on an extremely high dose of mind-altering drugs. And pretty much the same goes for state assistance. The only way the state will get involved in something like this is if there is a serious local effort, with serious grassroots support. So local efforts are really your only option. It will involve you and a lot of other people putting a large number of hours and a large amount of work into the project, all without any financial reimbursement. And if that goes well, you might possibly get state money or money from a battlefield preservation group put toward the effort, but that is not guaranteed. But flying monkeys will descend on the place before the federal government puts a penny into it.
I know this is not what you want to hear, but that is how things work. Hope you will excuse my cynicism, but I have been there and done that. On the up side, if it's done right on the local level, you can accomplish wonders, so things are not totally hopeless.