Grant's logistics turned losses into sustained pressure

What was the main lesson of Grant's final year of American Civil War campaigns?

Logistics, accounting, and replacement capacity let Grant continue operating after losses.

Grant's final campaigns provide an example of sustaining an army through repeated losses. Replacements could come forward after a reverse or the loss of a formation. Guns and ammunition also kept arriving because supplies were tracked and managed. The emphasis falls on the administrative work that allowed continued operations.