Written forty years ago, Divide and Rule is a socialist classic which argues that the partition of Ireland was a conscious act of the British ruling class in order to cut across a working-class movement with revolutionary potential. Importantly, it argues that this was not inevitable but that, with a socialist programme and the leadership, a united movement of workers have the capacity to cut across sectarian division, and challenge imperialism and capitalism itself. Herald Books, the publishing house of the Socialist Party, has reprinted Divide and Rule as we approach the centenary of partition, so workers and young people can draw the lessons of this historic period and apply them to the struggle for socialism today.