from reading fiction I'm given to understand that in the union army during the US civil war attrition in a unit was not addressed VIA replacements for the fallen soldiers, and rather new regiments where raised. is this true? and more importantly what if any was thought to be the virtues of this policy? and what where its flaws?
I can tell you that some units received replacement troops. My 3rd great grand Uncle was drafted and placed into the 49th Pennsylvania late in 1863. The 49th was originally mustered into service in September 1861. His name was William Bressler. He was absent because he ended up at Andersonville.