d of this army of invasion was General McDowell, held to be the
most scientific general in the North.

To supplement Beauregard's weakness as a commanding General in case of
emergency, Joseph E. Johnston was placed at Harper's Ferry to guard the
entrance of the Shenandoah Valley, secure the removal of the invaluable
machinery saved from the Arsenal, and form a junction with Beauregard
the moment he should be threatened.

The movement of General Patterson's army against Harper's Ferry had been
too obviously a feint to deceive either Davis or Lee, his chief military
adviser. Johnston was given ten thousand men and able assistants
including General Jackson.

On the tenth of July Beauregard, anxiously awaiting information of the
Federal advance, received an important message from an accomplished
Southern woman, Mrs. Rose O'Neal Greenhow. She had remained in
Washington as Miss Van Lew had in Richmond, to lay her life on the altar
of her country. During the administration of Buchanan she had been a
leader of Washington society. She was now a widow, noted for her wealth,
beauty, wit and forceful personality. Her home was the meeting place of
the most brilliant men and women of the old regime. Buchanan was her
personal friend, as was William H. Seward. Her niece, a granddaughter of
Dolly Madison, was the wife of the Little Giant of the West, Stephen A.
Douglas.

Before leaving Washington to become the Adjutant General of Beauregard's
army Colonel Thomas Jordan had given her the cipher code of the South
and arranged to make her house the Northern headquarters of the Southern
secret service.

Her first messenger was a girl carefully disguised as a farmer's
daughter returning from the sale of her vegetables in the Washington
market. She passed the lines without challenge and delivered her message
into Beauregard's hands.

With quick decision Beauregard called his aide and dispatched the news
to the President at Richmond:

"I have positive information direct from Washington that the enemy
will move in force across the Potomac on Manassas via Fairfax Court
House and Centreville. I urge the immediate concentration of all
available forces on my lines."

The Southern commander began his preparations to receive the attack.

The house on Church Hill had not been idle. Richmond swarmed with
Federal spies under the skillful guidance of Socola.

General Scott knew in Washington within twenty-four hours that