Impressment of Americans into British service and violations of American ships helped cause America's War of 1812 with Britain, which lasted until 1815. Virginians suffered under a British naval blockade of the Chesapeake Bay and from British troops plundering the countryside by the bay and along the James, Rapahannock, and Potomac rivers. Virginia militia deflected a British attempt to take Norfolk in 1813 and engaged British forces throughout the war, and by the end of the conflict more than 2000 enslaved African Americans in Virginia had gained their freedom aboard British ships. On 3 April 1813, at the mouth of the Corrotoman River, one of the largest naval engagements in Virginia waters during the war took place when 105 British naval and marine forces under Lt. Polkinghorne subdued four American privateers, Arab, Dolphin, Lynx, and Racer. The largest ship, Dolphin of Baltimore, carried twelve guns and one hundred men under Capt. W.J. Stafford, who refused to surrender after the other ships were taken and defended his vessel until he was severely wounded and it was boarded.