The most successful Confederate spy, in terms of turning in the most important and vital military information, was probably Washington socialite Mrs. Rose O'Neal Greenhow. Wealthy, educated, and widowed, Mrs. Greenhow used her luxurious home as the center of Confederate espionage activities, apparently making little or no effort to hide her support of the South. Arousing the suspicion of Federal authorities, Mrs. Greenhow was shadowed by Allen Pinkerton and arrested by Union forces for espionage. Despite being sentenced to house arrest, Mrs. Greenhow continued her work for the Confederate cause, including a secret mission to Europe in 1862. Greenhow drowned on the return voyage in 1864 when her ship ran aground near Fort Fisher.