She began her work in April, 1861, and by November Allan Pinkerton, head of the Federal Secret Service, sent in a report to the War Department vehemently inveighing against Mrs. Rose Greenhow for alienating the hearts of Federal officers from their sympathy with their country, and accusing her of obtaining through her wiles and powerful personal methods memoranda (and maps) which could only have been known to officials of the Federal Government. When the cry "On to Richmond!" was raised, it was absolutely essential for the Confederate Army under General Beauregard to have definite information about the point of attack. This data was furnished him by Mrs. Greenhow. She advised him that the enemy would advance across the Potomac and on Manassas, via Fairfax Court House and Centerville. The Federal Army delayed the advance, and a second messenger was sent to Mrs. Greenhow, who was able to add to her previous information, and on the strength of it Johnston was ordered to re-ënforce Beauregard with the last of his 8,500 men, and the wavering Federal Army turned back and fled in a rout--a mob of panic-stricken fugitives. It was soon known in Washington that Mrs. Greenhow had supplied the information upon which the Confederates had constructed their plans, and she was closely watched. Long after she knew that she must some day be arrested, she continued her activities, finding opportunities every day to communicate with Confederate officers, and her services were so valuable that she could not be persuaded to take refuge in the Confederate lines when there was so much work for her to do in the Federal Capital. She was in her own home when she was finally placed under arrest. Here she was closely guarded, but a friend and her little daughter were permitted to remain with her. In spite of the heavy guard, she continued to communicate with Southern messengers and kept them informed of what she heard. After a few months she was transferred to the Old Capitol Prison and kept in confinement with her child in a room 10 by 12. She suffered keenly in this cold and cheerless place. The soldiers who guarded her were very strict, but in spite of their closest scrutiny she managed under their very eyes to send messages to the people who were eagerly awaiting news of her on the other side of the lines. After tedious months of imprisonment she was tried[5] on the charge of treason. There was much direct and indirect evidence against her, but her attitude was uncompromising, and after the trial she was permitted to make her way through the lines to Richmond, where she spent some time until she took passage in a blockade runner with her daughter, whom she wished to place in a convent in Paris. She took with her letters to Mason and Slidell, which requested that every courtesy be shown her. In Paris she was given a private audience with Napoleon III.