The Siege of Fort Erie was one of the last and most protracted engagements between British and American forces during the Niagara campaign of the American War of 1812. From 4 August to 21 September 1814, the Americans successfully defended Fort Erie against a British army. During the siege, the British suffered heavy casualties in a failed storming attempt and also suffered from sickness and exposure in their rough encampments. Unaware that the British were about to abandon the siege, the American garrison later launched a sortie to destroy the British siege batteries, during which both sides again suffered heavy losses.