The Russian writer Isaac Babel (1894-1940) is acknowledged to be one of the great masters of 20th century literature, hailed as a genius by such critics as Lionel Trilling and Irving Howe. The work for which he is best known is a cycle of stories called Red Cavalry, which depicts the exploits of the Cossack cavalry during the Polish-Soviet war of 1919-1920 and is based on Babel's experiences as he rode with the Cossacks during the campaign. Babel kept a diary during this period, in which he recorded the devastation of the war, the extreme cruelty of the Polish and Red armies alike towards the Jewish population in the Ukraine and Eastern Poland, and his own conflicted role as both Soviet revolutionary and Jew. The 1920 Diary was a vital source for Red Cavalry as well as a compelling narrative. The 1920 Diary is a contemporary account of the tragedy of Eastern European Jewry during this period. The diary also yields insights into Babel's personal evolution, showing his youthful curiosity and his anguish as, frequently concealing his own Jewish identity, he mingled with the victimized Jews of the region's shtetls and with his Cossack comrades. Finally, the diary sheds light on Babel's artistic development, revealing the path of the Red Cavalry cycle.