Born in Port Tobbaco, Maryland, as a teenager O’Neal moved from her family’s Maryland farm to her aunt’s fashionable boardinghouse in Washington, D.C. Personable, intelligent, and outgoing, she adapted easily to the social scene of the capital, and people in Washington’s highest circles opened their doors to her. Regarded as a beautiful, ambitious, seductive woman, she disappointed an army of suitors by marrying Dr. Robert Greenhow, an influential, learned man under whose tutelage she flourished and to whom she bore 4 daughters.
Among her friends were presidents, senators, high-ranking military officers, and less important people from all walks of life, many of whom played knowing or unknowing roles in the espionage ring she organized in 1861. One of her closest companions had been John C. Calhoun, whose political instruction sealed Rose’s identification with and loyalty to Southern interests.
A widow when war broke out, Greenhow immediately used her contacts and talents to provide Gen. P.G.T. Beauregard with information resulting in the Union rout at First Bull Run.
Suspected of espionage and imprisoned Aug. 1861, she continued gathering and forwarding information vital to Confederate operations. News of her activities brought publicity and tremendous popularity among Southern sympathizers. After being brought to trial in spring 1862, Greenhow was deported to Richmond, where cheering crowds greeted her.
That summer Jefferson Davis sent her to Europe as a courier. She stayed there collecting diplomatic intelligence and writing her memoirs until recalled in 1864, apparently bearing dispatches urgent to the Confederacy. Sailing on the blockade runner Condor, she reached the mouth of the Cape Fear River just outside Wilmington, N.C., when a Union ship gave chase, forcing the Condor aground on a sandbar early on the morning of 1 Oct. Greenhow, fearing capture and reimprisonment, persuaded the captain to send her and 2 companions ashore in a lifeboat, but in stormy seas the small vessel overturned. Rose drowned, dragged down by the $2,000 in gold she carried. Her body was found and identified a few days later and buried with honors in Wilmington.