Gleditsch and Ward (1999) examined the criteria for membership in the international system employed by the Correlates of War (COW) project and developed a revised list of independent nation states since 1816. These revisions in turn have implications for other datasets based on the COW system membership classification. This article suggests various revisions to the COW project's list of wars to create a dataset compatible with the revised list of independent states. It identifies additional wars that qualify as interstate or civil wars as well as additional participating states to these wars. I show how the COW project's criteria, based on recognition by France and the UK to identify states as system members in the Nineteenth century and early Twentieth century, understate the total amount of conflict between and within the independent states identified by the Gleditsch and Ward list. An appendix to the article displays a revised list of wars since 1816, with updates for 1997 to 2002 based on data compiled by the Department of Peace and Conflict Research at Uppsala University, and details several changes to the current release of the COW war data over the previous 1994 ICPSR release. The article concludes by outlining an agenda for future collection and improvement of data on wars.
Gleditsch, Kristian Skrede (2004) A Revised List of Wars Between and Within Independent States, 1816-2002, International Interactions 30 (3): 231–262.