Go find your nearest Warrior Transition Unit at an Army base. Donate your money directly in terms of something they need. Buy them some special fitness equipment for adaptive sports training. Sponsor morale trips for the wounded Soldiers. Contribute to their recreation center. Fund their Christmas dinner. Find one who needs a special wheelchair or prosthetic, offer to pay for it.
We have guys that donate here in many ways. One guy runs outdoor trips all year round for the Wounded Warriors (hunting, hiking, camping, fishing, you name it). You could even donate the money to a research foundation that works on common problems such as amputees, PTSD, TBI or other conditions like orthopedics.
I just did a tour of the facilities at Fort Sam earlier this year. Center for the Intrepid was built by donation. Their recreation center was built by a private citizen donation.
I see you are in NC, you have a WTU at Bragg also one at Campbell in KY, 2 in GA at Benning and Gordon and I think there is a small one (company sized) in SC. Maybe check with the one in SC and see what they might need. It has always been my experience that the smaller separate units usually get the short end of the stick when it comes to funding.
Another thing you could do is simply volunteer your time. We have red cross volunteers and community volunteers who work with our Soldiers manning the activity center.
List goes on and on.