This is a red herring, listed here to correct what might be a misunderstanding. The Orphan Brigade had nothing to do with orphans or child soldiers or the Janissaries. The "Orphan Brigade" refers to units of Kentucky soldiers fighting for the Confederacy during the U.S. Civil War.
There are several stories of how the name came about. One states that it refers to the fact that they lost four major generals by death and transfer, and felt "orphaned." Another is related to the fact that since Kentucky was a Unionist state, and these men were fighting for the Confederacy, they could not recruit from home, go home on furlough, or even receive mail with regularity. As the war progressed and the Confederacy was seen to be losing, the men were also bereft of their government in Richmond and as traitors could not easily return to Kentucky, either.