Several years after his graduation in 1866, he worked as a surgeon in the Franco-Prussian War, and following his service, worked as a physician in in Prussian Posen (now Wolsztyn, Poland). From 1880 to 1885, Koch held a position as government advisor with the Imperial Department of Health. Koch began conducting research on microorganisms in a laboratory connected to his patient examination room. Koch's early research in this laboratory yielded one of his major contributions to the field of microbiology, as he developed the technique of growing bacteria. Furthermore, he managed to isolate and grow selected pathogens in pure laboratory culture.