Details the military aspects of the American Expeditionary Force's (AEF) deployment to Siberia following World War I to protect the Trans-Siberian Railroad. In the final months of World War I, President Woodrow Wilson and many US allies decided to intervene in Siberia in order to protect Allied wartime and business interests, among them the Trans-Siberian Railroad, from the turmoil surrounding the Russian Revolution. American troops would remain until April 1920 with some of our allies keeping troops in Siberia even longer. Few American citizens have any idea that the United States ever deployed soldiers to Siberia and that those soldiers eventually played a role in the Russian revolution while protecting the Trans-Siberian Railroad. Wolfhounds and Polar Bears relies on the detailed reports of the American Expeditionary Force (AEF) as well as on personal stories to bring this rarely discussed expedition to life. Initial chapters recount the period in World War I when conditions in Russia pointed to the need for intervention as well as the varied reasons for that decision. A description of the military forces and the geographic difficulties faced by those forces operating in Siberia provide the baseline necessary to understand the AEF’s actions in Siberia. A short discussion of the Russian Railway Service Corps explains their essential and sometimes overlooked role in this story, and subsequent chapters provide a description of actual operations by the AEF. Wolfhounds and Polar Bears: The American Expeditionary Force in Siberia, 1918–1920 may well be the most detailed study of the military aspects of the American intervention in Siberia ever undertaken, offering a multitude of details not available in any other book-length history.