Walter Reed had earned a medical degree by age 17 and joined the army as a surgeon at age 23. Reed had spent nearly 18 years at various western forts by the time he arrived at his post as curator of the Army MedicalMuseum in 1893, also working as a professor at the Army Medical School and at what is now George Washington University. As the 1890s started seeing important advances in medicine, Reed quickly moved to lead the charge against infectious disease, most notably yellow fever.

Yellow fever had been a horrible scourge in the United States for generations. The virus initially causes headaches, nausea, fever, fatigue, and muscle aches. Over the next two days, the fever spikes, causing delirium and seizures. It can also cause liver and kidney failure, leading to death within a couple of days. The yellowing of the skin and the eyes in this final stage is caused by the severe damage to the liver and is where the disease gets its name.

Outbreaks terrified communities. A yellow fever outbreak in Philadelphia in 1793 left more than 3,000 dead. The disease often travelled along the steamboat routes up and down the Mississippi River and along the Ohio and Missouri Rivers, for reasons that mystified doctors in the 1800s. The “Yellow Jack,” as it was called, killed thousands in outbreaks in New Orleans and Memphis and reached across the Gulf and Atlantic coasts. An 1878 outbreak left nearly 20,000 people had died in the Memphis area, and the city government and economy had collapsed.

The mystery of diseases like yellow fever prompted Reed to want to learn more and immerse himself in the latest studies in the field. Colleagues were quick to point out that Reed’s time in the field had actually sharpened his medical skills. Reed had learned to be a careful observer, a strict disciplinarian when it came to hygiene and research, and developed a compassionate bedside manner. Often, he begged his wife to allow him to bring his youngest patients, the young children of frontier settlers and Native Americans from reservations, to convalesce in their home.

He would end up writing dozens of articles for medical journals. In 1895, he began calling for cities to develop their own supplies of medications like the new diphtheria antitoxin and insisted that testing of new medicines should be completed by neutral scientists without any monetary interest.

During the Spanish-American War of 1898, most American deaths were from disease rather than gunfire. Reed was appointed chairman of a committee to study an outbreak of typhoid fever among troops during the war. The two-volume study that resulted was considered groundbreaking at the time.

In 1900, Reed was named chairman of the Yellow Fever Commission to study outbreaks of the disease in Cuba during the war and across the US. The previous research of Cuban physicians such as Dr. Juan Guiteras and Dr. Carlos Finlay proved indispensable to Reed and the Yellow Fever Commission, suggesting that microorganisms from mosquitoes were responsible for its spread. Though many doubted the mosquito theory, Reed was convinced and organized a series of experiments. Two volunteers, including a commission doctor, agreed to be bitten by the mosquitoes to see whether they spread the disease. They both developed yellow fever. Two dozen other men volunteered for a series of experiments to test it further, proving that mosquitoes carried the virus. Immediately, mosquito eradication became a priority across the South and in Cuba. Reed’s experiments made him a hero across the country.

In November 1902, however, his appendix ruptured. Reed died at the age of 51.

Reed continued to be a revered figure across the nation in the years after his death. Yellow fever rapidly receded, with the America’s last city-wide outbreak occurring in New Orleans in 1905; and a vaccine was developed in 1937. His fellow physicians pushed for a new army hospital to be built and named after him as a testament to his work. The first building of what was then Walter Reed General Hospital opened in May 1909 at a cost of $192,000 (or $5.7 million in 2020 dollars). It steadily grew into a complex of buildings. In 1923, the Army Medical School was moved to the Walter Reed complex. Over the years, thousands of veteran service members and many prominent politicians received treatment, from minor ailments to complex surgeries and lengthy rehabilitation for injured troops, at Walter Reed in its decades of service at its original location.

Reed’s own son, Walter Lawrence Reed, embarked on an army career, rising to the rank of major general. General Reed died in 1956 at the age of 78 in the hospital that bore his father’s name.

Perhaps the most fitting legacy was in the years after his death, yellow fever was effectively eliminated in the United States, and communities across the nation no longer had to live in fear of the dreaded epidemic. A century later, the disease is almost unheard of in the United States.