Although there are ratings that have been in official use longer than Hospital Corpsman (HM), the position has been around as long as there has been a United States Navy.
It was in 1814 that Navy Regulations first made reference to a “loblolly boy,” an assistant to the surgeon and surgeon’s mate responsible for handling the ancillary jobs associated with shipboard surgery. Because amputation was far and away the most common procedure for dealing with serious wounds such as compound fractures or severed arteries and veins, one of the loblolly boy’s duties before battles was to pour water into containers that were used for disposal of amputated limbs (why these were not simply tossed overboard is an unsolved mystery). He also had to keep braziers filled live charcoal to be used for cauterizing wounds, and pour sand on the deck around the operating area to keep the surgeon and other crew members from slipping.
The rather undignified “loblolly boy” was transformed into Nurse at the start of the Civil War and then to Bayman in 1976; the rate for senior enlisted medical personnel became Surgeon’s Steward in 1841 and then Apothecary in the post-Civil War era. (Along with the new Apothecary rate came a requirement to complete a pharmaceutical training course.)
It was not until the end of the 19th Century that the U.S. Navy established the direct predecessor to the Hospital Corpsman rating: Hospital Corps. When it was created in 1899, there were only three rates: Hospital Apprentice, Hospital Apprentice First Class, and Hospital Steward (a CPO). The rating was expanded in 1916 to provide for two rates of Hospital Apprentice and Petty Officers being called Pharmacist’s Mates and following the naming conventions of other ratings. A Pharmacist’s Mate promoted to Chief Petty Officer, for instance, would be called a Chief Pharmacist’s Mate.
In 1948, the Hospital Corpsman rating was finally established, with an apprentice in the rating known as a “Hospitalman.” Currently, over 24,000 Sailors serve as Hospital Corpsmen, with almost half of them going on to receive further specialized training that provides them with advanced expertise in a broad variety of technologies involving the treatment of disease and injuries.