@Alyssa K. - This is critically important, but as far as I can tell nobody has yet mentioned it. However, this is something every landlord near a military installation should be aware of:
The Servicemembers Civil Relief Act (50 U.S.C. §§ 3901-4043) is a FEDERAL law aimed at establishing civil protections for active duty servicemembers. It offers many protections for active duty servicemembers, including against certain default judgments, certain foreclosures, repossessions, and, among other things, early termination of leases.
Hearkening back to civics class - the supremacy clause means that Federal laws trump all State laws. States can offer MORE civil protections for citizens than the Federal government, but not fewer.
Now, to your specific situation: 50 U.S.C § 3955 is the statute dealing with early termination of residential leases for active duty servicemembers. Section (e)(1) details that a landlord may not impose any early termination fees for an early-termination of the lease that qualifies under the statute. To do so could be (depending on the circumstances) a misdemeanor (!!!) under this statute (see section H - withholding of property). Hopefully that answers your question long-term.
For further clarification on the supremacy clause and the SCRA generally, see below.
Navigating the supremacy clause specifically - Let's use a hypothetical: Let's say there's a statute in State X that says "Military members shall be allowed to terminate their lease early so long as they deploy for a period of no fewer than 15 days". This state is doing okay so far. They have further extended civil protections beyond what the Federal Government requires. That's constitutionally correct. Now let's say State Y says "Military members shall be allowed to terminate their lease early so long as they deploy for a period of no fewer than 360 days." That's a big no-no. Boooooo State Y! The Federal Government has already established 90 days as the minimum, so you can't further restrict their civil protections to make them less protective than the Federal Government has. Make sense? The upshot is that if the Federal Government has a statute on point, and if there are any state statutes that cover the same ground they will offer further protections to servicemembers.
Side note - lots of landlords will include a "military clause" in their lease that repeats the protections of the SCRA. I've had landlords tout that to me as if they're doing me a favor. I'm like "Cool story, bro. But I'm covered by the Federal Government already, so that language is superfluous. If you didn't have it in the lease, the Federal Government laws would still apply. So don't act like you're doing me a favor."
All that said, you must ensure that your lessee actually qualifies under this statute. The active duty servicemember must, to qualify under the SCRA, receive either PCS orders or be deploying for a period of over 90 days. (Alternately, instead of orders, they can give notice via a letter from their commander, because as @Luke Sanderson mentions above, orders can come in much, MUCH later than when a servicemember is notified that they will PCS. My buddy, for example, knew in April that he would PCS to the National Capital Region last summer from Fort Carson, CO. He didn't receive his official orders until two weeks before the move in June (it caused all sorts of issues).) Keep in mind that many official-looking documents are not, in fact, orders. Like a DA 4187, for example. We use those for interpost transfers and for marking people AWOL - they're certainly not PCS orders. In other words, ensure that the orders are in fact orders and that they qualify under the SCRA.
Likewise, don't be afraid to call the installation and ensure that the orders are legit. Sadly, some servicemembers try to take advantage of the generous benefits bestowed on them by the Government and use it to their advantage. I've seen fake orders to break a lease come up three times so far in my Army career. It's upsetting, but be aware that there are dirtbags in the military just like there are dirtbags in the civilian population. And a commander will want to know if one of their servicemembers is trying to take advantage of the good will of the civilian population for their own personal gain.
Hopefully that covers what you were asking about. If you have other questions about the special protections of the military in the context of residential leasing, please don't hesitate to reach out.