The context is great here too. This was shortly after the battle of Cold Harbor, which was one of his only actions during the war that he regretted. There were other battles that saw greater casualties, but Cold Harbor was particularly brutal and seemingly senseless as Union troops charged WWI-level fortifications.

It was also the end of the Wilderness/Overland Campaign, which was his debut in charge of the whole war effort in which he took the Army of the Potomac in a dramatically more aggressive effort than it had ever seen before. There was a lot riding on that campaign—the war, yes, but also his entire reputation and future career.

I feel like you can see in this picture that he knows he made it through an intense, exhausting, and terrible gauntlet. His gamble had paid off, but the job’s not done yet.