The nationalistic sentiment caused suspicion of such American ideas as republicanism, which would frustrate political reform in both Upper and Lower Canada until the Rebellions of 1837. However, the war started the process that ultimately led to Canadian Confederation in 1867. The Canadian writer Pierre Berton wrote that although later events, such as the rebellions and the Fenian raids of the 1860s were more important, Canada would have become part of the United States if the war had not taken place since American settlers would have continued to arrive and so Canadian nationalism would not have developed.