At least 13 police officers were injured on Sunday in clashes between Catholics and Protestants in Northern Ireland. Police fired water canons while protesters threw bottles and stones at the officers. The clashes began after a Catholic Irish nationalist band marched in an area where pro-British Protestants have been prohibited. After three decades of violence known as “the Troubles,” Northern Ireland has been relatively peaceful since the Good Friday peace accords in 1998, but its capital city, Belfast, has remained divided along religious lines. Sunday’s disturbances came after seven police officers were injured last weekend in the same area when a Protestant band marched past a Catholic church, playing music in defiance of a ban from the parades commission.