Army, Navy, Air Force all offer PA school. The entire concept of the PA, in fact, was pretty much a military invention back in the Vietnam era I believe. While I have not gone to PA school, I can tell you that the Army PA program (run in San Antonio) is pretty good judging from the PA's I have worked with. The program is 2 years long; 1st year is classroom and done at Ft Sam Houston in San Antonio. For the second year you do clinical rotations at an Army hospital somewhere. There are opportunities for PAs to subspecialize (ortho, surgery, medicine, etc) but I'm not sure if those are run by the military itself or if you are deferred to civilian programs for further training.