Those who came in the earlier period were largely tradesmen, and many stayed in Saint John, becoming the backbone of its builders. But when the Great Famine of Ireland raged between 1845 and 1849, huge waves of famine refugees flooded the city's shores. It is estimated that between 1845 and 1847, some 30,000 arrived, more people than were living in the city at the time. In 1847, dubbed "Black 47", one of the worst years of the famine, some 16,000 immigrants, most of them from Ireland, arrived at Partridge Island, the immigration and quarantine station at the mouth of Saint John Harbour.