What happened to the tens of millions of guns left over from World War I? In Counterterrorism Between the Wars, Mary S. Barton argues that the Great Powers’ failure to secure them contributed to rise of state-sponsored terrorism during the 1920s and 1930s. Barton tells a global story of the demise of empires, the rise of communism, and the cooperation between the United Kingdom and United States that would evolve into the Five Eyes intelligence alliance.

Mary S. Barton is an Intelligence Research Specialist (Cyber Threat Analyst) with the Financial Crimes Enforcement Network, Department of the Treasury. She received her Ph.D. from the University of Virginia in 2016. She completed postdoctoral fellowships at the Henry A. Kissinger Center for Global Affairs, SAIS, and Dartmouth College, and previously served as a historian and wargaming analyst supporting the Office of the Secretary of Defense.

The Washington History Seminar is co-chaired by Eric Arnesen (George Washington University and the National History Center) and Christian Ostermann (Woodrow Wilson Center) and is organized jointly by the National History Center of the American Historical Association and the Woodrow Wilson Center's History and Public Policy Program. It meets weekly during the academic year. The seminar thanks its anonymous individual donors and institutional partners (the George Washington University History Department and the Lepage Center for History in the Public Interest) for their continued support.