When people think of Irish emigration, they often think of the Great Famine of the 1840s, which caused many to flee Ireland for the United States. But as Sean Connolly points out, the Irish diaspora has been much longer, more complicated, and more global. Starting in the 18th century, the Irish fanned out across North America and Australia, settling frontiers, industrializing the West, and spreading Catholicism. As the Irish built vibrant communities abroad, they leveraged their newfound power—sometimes becoming oppressors themselves.