Historical Basis for this movie
Like most movies set in this time period (Old West and Civil War) this movie actually has an historical basis. By late 1862 some Texas Confederates were POWs and interned in Minnesota. Due to the Civil War most of the U.S. Army troops had been taken out of Minnesota and sent southward towards the battle zones. This left the frontier in Minnesota open to attacks by Indians (as the native North Americans were called then), and, in fact, quite a few attacks occurred on settlers in that area. The United States needed manpower to fight off these attacks but from where could they get the soldiers?
The Army realized the Texas POWs probably had some experience in that sort of warfare so they offered them the opportunity to serve in the U.S. Army with the understanding they would only fight the Indians and never be deployed anywhere near where they might have to fight any Confederates. Quite a few took up the offer and served, quite well, on the Northern frontier. After the war they were released and made their way back to Texas. There was not near the acromony in real like that the movie showed, and the soldiers were successful. Also, unlike the movie, this took place in the Northern frontier; not the Southern one so Mexico was not involved.
Interestingly enough, some years after the Civil War ended the various states offered pensions to their veterans. The Texas soldiers obtained a pension form Texas, of course, but what is VERY interesting is that these soldiers also qualified for, and received, pensions from Minnesota- a Union State! They were probably the only Confederates who received Union pensions. It would have been interesting to see these soldiers at Civil War reunions (such as occurred at Gettysburg in 1938) and see which side they were on at the reunion! Hmmm...perhaps they wore their Confederate uniforms on Monday, their Union uniforms on Tuesday, back to the Confederate uniform on Wednesday.....Anyway, it does uphold the old saying about Texas producting some of the best soldiers....no matter which side they serve on!!!!!! ;)