Walter Reed was born in 1851 in Gloucester, Virginia, the son of a traveling Methodist minister. He earned a medical degree from the University of Virginia before turning 18, still the youngest ever there, and a second in New York by 1870. After passing a 30-hour exam he joined the Army Medical Corps in 1875 and spent 16 years in the West, treating soldiers, Geronimo’s Apaches and pioneers, saving Jules Sandoz’s shattered foot from amputation, and adopting a Native American daughter named Susie. Study at Johns Hopkins drew him to germ theory, and in 1896 he traced a malaria and typhoid outbreak near the Potomac to enlisted men walking through swamps at night, while officers drinking the same river water stayed healthy.

In Cuba in 1898 he showed typhoid was carried by flies from latrines to food. In 1900 Surgeon General George Miller Sternberg sent him to lead the Yellow Fever Commission in Cuba, where he tested Cuban doctor Carlos Finlay’s 1881 mosquito theory at Camp Lazear. Volunteers slept 20 nights in bedding soiled by yellow fever victims and none fell ill, while others let infected mosquitoes bite them. Jesse Lazear died of the disease at 34. William C. Gorgas used the findings to wipe out mosquitoes in Havana and Panama, opening the way for the canal. Reed died of a ruptured appendix in 1902 at 51.

• The French canal effort, which lost about 10 percent of its workforce each year to yellow fever and malaria
• Why the fomite theory blamed soiled clothing and bedding for spreading the disease
• The two cabins: one sealed against mosquitoes, one split by wire mesh with infected mosquitoes on one side
• Volunteers paid in gold, and the questions about consent inside a military hierarchy
• Reed crediting Finlay, his burial at Arlington and the Walter Reed National Military Medical Center