May 23rd 1865. The Army of the Potomac paraded through Washington, DC, to mark the end of the Civil War. By the end of this five-year conflict, the nation had a million men in uniform, and an army that the world envied and feared. To many students of the war, this army was the emblem of what the war had wrought—a modern state. The United States government had grown in size, capacity and capabilities; had levied its first income tax; and had become a nation-state at last.