Cork is a city in Ireland. It is located in the South-West Region and in the province of Munster. With a population of 119,230, it is the second largest city in the state and the third most populous on the island of Ireland. The city is built on the River Lee which divides into two channels at the western end of the city. The city centre is located on the island created by the channels. At the eastern end of the city centre where the channels re-converge, quays and docks along the river banks lead to Lough Mahon and Cork Harbour, which is one of the world's largest natural harbours. The city's cognomen of 'the rebel city' originates in its support for the Yorkist cause during the War of the Roses. Corkonians often refer to the city as 'the real capital' in reference to the city's role as the centre of anti-treaty forces during the Irish Civil War.