Although the Russian Imperial Army Air Service consisted of no more than four BAGs (Boevaya Aviatsionniy Gruppa - battle aviation groups), each controlling three or four smaller AOIs (Aviatsionniy Otryad Istrebitelei - fighter aviation detachments) equipped with a variety of aircraft types, its fighter pilots nevertheless gave a good account of themselves. Indeed, during three years of war they claimed more than 200 Austro-Hungarian and German aircraft shot down, creating 13 aces - these elite aviators accounted for around half of the victories claimed on the Eastern Front. Pilots flew a variety of fighter types, with French Nieuport scouts and SPAD VIIs proving to be the most popular, and effective, aeroplanes to see service on this front. The exploits of these aces are detailed here, with information based on material newly sourced by the author from Russian military and private archives. Many previously unpublished photographs are used to illustrate this book, supported by full-colour profiles that reveal how striking some of the aces' fighters were in this often-forgotten theatre of World War 1.