Confederate President Jefferson Davis credited her with winning the battle of First Manassas. Her name? Rose O'Neal Greenhow (1817-1864). According to wikepedia she was a fearless spy for the Confederacy as well as a glittering Washington hostess.
Rosie paid the price for her accomplishments, as she was imprisoned for her efforts. Even then she continued getting messages to the Confederates by means of cryptic notes, which traveled in unlikely places such as in a woman's bun of hair.
After her second prison term she was exiled to the South, where she was warmly received by Davis, who sent her to Britain and France on behalf of the Confederate cause.
In 1864 she boarded a ship for home. The vessel ran aground near Wilmington NC and she fled in a rowboat but never made it to shore. The little boat capsized and she was dragged down by the weight of the gold she was bringing back to aid the Confederate cause.
She was buried with full military honors and her coffin was wrapped int the Confederate flag and carried by Confederate troops. The marker for her grave, a marble cross, bears the epitaph, "Mrs. Rose O'N Greenhow, a bearer of dispatches to the Confederate Government".
There is a book about her if you want to read more: "Rose O'Neal Greenhow, Civil War Spy".