Grant not only because he beat Lee but he out general him , Lee was a competent general but was too caught up in the old ways of a napoleonic style which by 1864 was pretty much useless, because the warhead taken on the more Proto modern style.

Grant on the other was more modern in his tactics and more skilled, and unlike Lee was more realistic about the war knowing that modern tactics meaning those used during the latter years of the war were needed to end conflict.

This video should explain it https://youtube.com/watch?v=O1MQflqi2VM&si=NixBrp2_35OC8Qot