Up until July 31, 1864, I think Grant was fighting Lincoln's war. After that, the Farragut operation closed Mobile Bay. Warren got to the Weldon RR, and Hill's corp could not knock the US off the road. That improved Sherman's chances in Georgia, and he first captured Atlanta and then knocked Georgia out of the war after the election.
In the east, a small, but critical operation was sinking the Albermerle. Grant seems to have put a high priority on also closing Wilmington. Because while Sherman was marching toward the coast, Warren extended his raid down the Weldon RR. When Butler failed to follow orders and hold his position in NC, he was immediately fired, and David Porter was more or less given command of the combined arms operation to take Fort Fisher.
The simultaneous pressure begins to mount after August 1, 1864. No, it was not a war of attrition, though part of it looked that way.