On Every Tide is an immensely impressive, authoritative history of the Irish diaspora. Calling on thirty years of research, Sean Connolly broadens out the conventional stereotypes of the downtrodden masses fleeing oppression and starvation, and looks at the individual stories and local forces that propelled individuals and families and communities of Irish to come over to England, or cross the Atlantic, or go much further afield to South Africa, Australia and elsewhere. Irish migration happened so far in advance of the other mass migrations from Europe, and in such great numbers, that they had dug in to the local economies, planted themselves at the centre of politics and policing, and stamped their identities indelibly on New York, Boston, Sydney and elsewhere before all those other nationalities turned up en masse. Inevitably they took with them all the divisions - religion, class, status - from their homeland and in many cases replicated them where they arrived. But alongside the export of street politics, sectarianism and militant trade unionism there are the energetic businessmen, famous public-spirited dynasties and generations of enfranchised women finding the kind of freedom they couldn't achieve in Ireland. It's a complex and fascinating picture, animated for us though a multitude of stories.The book follows the story through the great nineteenth century famines and into the twentieth century, where the question of Irish emigrant identity becomes a lot more opaque: intermarriage and global travel and the mythologizing of Ireland lead to far more people claiming an Irish identity around the world than have actual roots there. The book plays directly into the wider debates about migration that are swirling around now, as well as offering a unique and distinctive view of 200 years of Irish history.