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COW Wars


The COW Project introduced COW Wars v4.0, 1816-2007 in 2010. The paper “The COW Typology of War: Defining and Categorizing Wars (Version 4 of the Data) by Meredith Reid Sarkees gives an overview of the COW war typology, the descriptions of the basic variables, coding rules and some of the changes since “Resort to Arms.” In March 2010, the New COW War List was released. On June 30, 2010, the Non-State War Data (v4.0) became available. On October 28, 2010, the Intra-State War Data (v4.0) was released and on April 6, 2020 the Intra-State War Data (v5.1) became available online. On March 1, 2011, the Inter-State War Data (v4.0) became available online. Finally, we released the Extra-State War Data (v4.0) on December 8, 2011. 



We ask users of the data set to cite this data set as follows:

Sarkees, Meredith Reid and Frank Wayman (2010). Resort to War: 1816 - 2007. Washington DC: CQ Press.

Questions and Feedback

The war data sets are hosted by Meredith Sarkees, Global Women's Leadership in International Security, and Frank Wayman, University of Michigan-Dearborn, under the COW Data Set Hosting Program. In case of questions, they may be contracted by email at and .