By any standards, Waldermar Lotnik's experience of the Second World War was remarkable. Fighting in the Polish Resistance, his unit was engaged in a bitter ethnic conflict with pro-Nazi Ukrainians. Unknown in the West, this struggle was, like that raging at the same time between Serbs and Croats, provoked by the Germans arming one ethnic group and unleashing it against a rival. Lotnik described with total and sometimes frightening candour his part in a war without rules that claimed at...