Battle of Spotsylvania
"In the end, the battle was tactically inconclusive, but both sides declared victory. The Confederacy declared victory because they were able to hold their defenses. The United States declared victory because the Federal offensive continued and Lee's army suffered losses that could not be replaced. With almost 32,000 casualties on both sides, Spotsylvania was the costliest battle of the campaign." - https://en.wikipedia.org/wiki/Battle_of_Spotsylvania_Court_House
