Which corps did Fleming serve in during World War I?

During World War I, Alexander Fleming served in the Royal Army Medical Corps. He worked as a bacteriologist with military medical teams, studying the infections that devastated soldiers with battlefield wounds.

Fleming had been connected with the London Scottish Regiment before the war, which can cause confusion about the corps in which he served. In 1914 he received a commission as a lieutenant in the Royal Army Medical Corps and was promoted to captain in 1917.

Much of his wartime work took place at hospitals on the Western Front, including the laboratory established at Boulogne under Sir Almroth Wright. Fleming examined wound bacteria and saw that antiseptic treatment could sometimes damage tissue while failing to control infections deep inside wounds.

The experience strongly influenced his later research. After returning to St Mary’s Hospital in 1918, he continued studying antibacterial substances. His wartime observations formed an important background to his later discoveries of lysozyme and penicillin, though penicillin itself was identified in 1928.