The First War with Mass Vaccinations of the Troops

In this photograph, soldiers of the Liverpool Scottish show off their arms
after being vaccinated, c.1914.

Many of the most important medical developments and practices of the last century have their origins in the First World War. Vaccines were first used on a major scale during the war and most British servicemen sent abroad were vaccinated against typhoid. As a result, deaths from the disease were significantly reduced. 

For the British Army this was due to one not well known event, when Sir William Osler, Regius Professor of Medicine at Oxford University, persuaded senior army officers about the necessity of vaccinating troops against typhoid, despite a conscientious objector law preventing compulsory vaccination backed by the powerful Anti-Vaccination League. Osler argued that the "army marched on its brain" and that vaccination against typhoid would reduce mortality by half. In the event, Osler’s arguments won the day and soon 97 percent of the troops were being vaccinated. It is worth pointing out that by 1911, vaccination against typhoid was mandatory for American troops, and one of the reasons for the low mortality from disease in the 1904–05 Russo-Japanese War was that the Japanese vaccinated all their troops against typhoid. By 1914 there were also vaccines against cholera, anthrax, rabies, typhoid, and plague, but they appear to have been used randomly without any obvious strategic plan.

Sources:  Imperial War Museum; "The First World War Disease the Only Victor," Lecture by Professor Francis Cox, Gresham College