This review suggests that recent historiography on nationalism can help us to see that the English Civil War was, in part, a conflict about national identity and ethnic difference. It argues that, even before the war began, the supporters of the parliament were associated with a narrowly intolerant strain of Englishness, and that this helps to explain why the Celtic peoples of Wales and Cornwall rallied to the king. During 1642–4, parliament's close links with the Scots – together with the presence of many foreign mercenaries in the roundhead armies – prevented the identification of parliament's cause with that of England itself from becoming absolute. Following the creation of the New Model Army, however – an army from which ‘strangers’ of all sorts were deliberately excluded – relations between the Scots and parliament rapidly deteriorated, and it became possible for the parliamentarians to make an unequivocal appeal to English patriotic sentiment. The defeat of the king – and of the Welsh and Cornish troops who had done much to sustain his cause – was the result.