Robert Koch's identification of the tuberculosis pathogen in 1882 is held to be his greatest scientific achievement. In the eyes of his friend and colleague, Friedrich Löffler, the discovery was a “world-shaking event” which resulted in both instant and everlasting fame, turning Koch “overnight into the most successful and outstanding researcher of all times”. Paul Ehrlich, remembering Koch's presentation in Emil du Bois Reymond's Institute for Physiology in Berlin on 24 March 1882, called it “my single greatest scientific experience”. The sensational character of Koch's achievement, which is noted in Löffler's and Ehrlich's retrospective statements, seems to have been obvious to contemporaries of the event. Albert Johne, writing a history of tuberculosis in 1883, found that history had, in a way, come to an end: “resulting from the latest of Koch's publications, the pathogenic aspects of the tubercle question are settled at large”. Koch himself profited from the overwhelming reception by being promoted to the rank of a senior executive officer, Geheimer Regierungsrath, in June 1882. March 24, 1882 thus came to stand for two things: Koch's breakthrough to world fame and a sort of doomsday for tuberculosis. Not surprisingly, the event was held in similar esteem by later biographers: Bernhard Möllers in 1950 called it the “greatest and most important success of his life”, and Thomas Brock, Koch's most recent biographer, assessed the discovery of the tubercle bacillus as the first of two steps on Koch's road to fame in the early 1880s. In conjunction with the 1883–84 cholera expedition, which made Koch a hero for the public, the tubercle bacillus indicated his breakthrough in the scientific world.