For much of the war, the massive Union Army of the Potomac made up the second-largest population center in the Confederacy, and each morning this sprawling city became a coffee factory. First, as another diarist noted, “little campfires, rapidly increasing to hundreds in number, would shoot up along the hills and plains.” Then the encampment buzzed with the sound of thousands of grinders simultaneously crushing beans. Soon tens of thousands of muckets gurgled with fresh brew.