The Order of Knights of the Hospital of Saint John of Jerusalem, commonly known as the Knights Hospitaller, is a Catholic military order. It was founded in the crusader Kingdom of Jerusalem in the 12th century and had its headquarters there, in Jerusalem and Acre, until 1291, thereafter being based in Kolossi Castle in Cyprus (1302–1310), the island of Rhodes (1310–1522), Malta (1530–1798), and Saint Petersburg (1799–1801). The Hospitallers arose in the early 12th century at the height of the Cluniac movement, a reformist movement within the Benedictine monastic order that sought to strengthen religious devotion and charity for the poor.