The Battle of Grand Gulf was fought on April 29, 1863, during th: Northern Ireland, separated from Great Britain by the Irish Sea and North Channel, has an area of 5,470 square miles (14,160 km2) and is mostly hilly. It includes Lough Neagh which, at 150 square miles (388 km2), is the largest lake in the British Isles by area,[157] Lough Erne which has over 150 islands and the Giant's Causeway which is a World Heritage Site. The highest peak in Northern Ireland is Slieve Donard in the Mourne Mountains at 852 metres (2,795 ft).[151]