Teaches military history, with special emphasis on war and society in the modern age outside of the United States. Professor MacKenzie regularly offers upper-level undergraduate courses on the Evolution of Warfare (2500 BC to 1500 AD and 1500 AD to the Present), War and Society in Twentieth-Century Europe, The Historian’s Craft (for History Majors), and, on occasion, Twentieth-Century Britain. At the graduate level he offers reading and special topics courses, when requested, on Modern Europe and on War and Society.

His book publications include:

• The Imjin and Kapyong Battles, Korea 1951 (2013)
• British Prisoners of the Korean War (2012)
• Bader's War (2008)
• The Battle of Britain on Screen: 'The Few' in British Film and Television Drama (2007)
• British War Films, 1939-1945: The Cinema and the Services (2006)
• The Colditz Myth: British Prisoners of War in Nazi Germany (2004)
• Revolutionary Armies in the Modern Era: A Revisionist Approach (1997)
• The Home Guard: A Military and Political History (1995)
• Politics and Military Morale: Current-Affairs Education in the British Army, 1914-1950 (1992)