The Russian writer Isaac Babel (1894-1940) is widely acknowledged to be one of the great masters of twentieth-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 calledRed 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 toward the Jewish population in the Ukraine and eastern Poland, and his own conflicted role as both Soviet revolutionary and Jew. The1920 Diary, a vital source forRed Cavalryas well as a compelling narrative, is now published in English for the first time.The1920 Diaryis the most significant contemporary account of the tragedy of Eastern European Jewry during this period. TheDiaryalso yields important 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, theDiarysheds light on Babel's artistic development, revealing the path from observations recorded in excitement and despair to the painstakingly crafted narratives of theRed Cavalrycycle.