This is coolbert:
This was a totally new one on me. Those of you who have seen the mid-1960's Charlton Heston movie "Major Dundee" will understand instantly that the adage: "truth is stranger than fiction" is factual in basis.
From that wiki entry Penal Military Unit under the heading of United States we have the topic of what was referred to as the "Galvanized Yankee".
"Galvanized Yankees; during the American Civil War, Confederate prisoners of war who swore allegiance to the Union were allowed to join the Union Army and serve on the western frontier."
Galvanized Yankees not necessarily as I might suggest in the category of a penal unit as that term generally, ordinarily and commonly understood.
Confederate prisoners of war [POW] being given a parole and release under conditions with terms.
Confederate POW recruited and swearing allegiance to the Union and Federal forces.
But with the proviso that they serve the Federal cause ONLY on the western frontier and NOT in combat with their former countrymen [Confederates].
Galvanized Yankees those Confederates serving in U.S. Army units and in mortal combat with those American Indian nations deemed as "hostile".
Many [perhaps the overwhelming number so] not necessarily responding to the cause of the Union but rather merely to escape the danger of a POW camp.
Those Union and Confederate POW camps of the era abominations, deadly to the inmates, the mortality rate from disease just terrible.
Enlistment in the detachments of Galvanized Yankees a way out of misery WITH HONOR, NOT A BETRAYAL OF THE CAUSE!
Consider that the largest mass grave in all of North America is in Chicago, Illinois, USA, four thousand bodies of Confederate troops as held at Camp Douglas perishing from typhoid fever.
Even more so that combat, languishing in a POW camp during the American Civil War was potentially more hazardous to your health.
Understand too that typhoid fever the illness as acquired from the drinking bad water. Historically speaking water either having too little to drink or drinking of BAD water a killer of soldiers beyond that of battlefield deaths.