In 1924, six years after the end of hostiliies, the painter Otto Dix, who had been a machine-gunner in the German Army, produced his 51 Der Krieg prints. Gruesome, hallucinatory, and terribly frank, these postcards of conflict tell the soldier's ghastly tale. Cartoonist Martin Rowson, whose own work is similarly direct and uncompromising, tells Dix's story and ponders why Der Krieg remains such a powerful statement.