The Union advance was retarded by the condition of the weather and the roads. Between McClellan's position at White House and the waiting Confederate army lay the Chickahominy, an erratic and sluggish stream, that spreads itself out in wooded swamps and flows around many islands, forming a valley from half a mile to a mile wide, bordered by low bluffs. In dry weather it is but a mere brook, but a moderate shower will cause it to rise quickly and to offer formidable opposition to any army seeking its passage. The valley is covered with trees whose tops reach to the level of the adjacent highlands, thus forming a screen from either side. The bridges crossing it had all been destroyed by the retreating army except the one at Mechanicsville, and it was not an easy task that awaited the forces of McClellan as they made their way across the spongy soil. The van of the Union army reached the Chickahominy on May 20th. The bridge was gone but the men under General Naglee forded the little river, reaching the plateau beyond, and made a bold reconnaissance before the Confederate lines. In the meantime, newly constructed bridges were beginning to span the Chickahominy, and the Federal army soon was crossing to the south bank of the river. General McClellan had been promised reënforcements from the north. General McDowell with forty thousand men had started from Fredericksburg to join him north of the Chickahominy. For this reason, General McClellan had thrown the right wing of his army on the north of the river while his left would rest on the south side of the stream. This position of his army did not escape the eagle eye of the Confederate general, Joseph E. Johnston, who believed the time had now come to give battle, and perhaps destroy the small portion of the Union forces south of the river. Meanwhile, General "Stonewall" Jackson, in the Shenandoah, was making threatening movements in the direction of Washington, and McDowell's orders to unite with McClellan were recalled. The roads in and about Richmond radiate from that city like the spokes of a wheel. One of these is the Williamsburg stage-road, crossing the Chickahominy at Bottom's Bridge, only eleven miles from Richmond. It was along this road that the Federal corps of Keyes and Heintzelman had made their way. Their orders were "to go prepared for battle at a moment's notice" and "to bear in mind that the Army of the Potomac has never been checked." Parallel to this road, and about a mile to the northward, runs the Richmond and York River Railroad. Seven miles from Richmond another highway intersects the one from Williamsburg, known as the Nine Mile road. At the point of this intersection once grew a clump of seven pines, hence the name of "Seven Pines," often given to the battle fought on this spot. A thousand yards beyond the pines were two farmhouses in a grove of oaks. This was Fair Oaks Farm. Where the Nine Mile road crossed the railroad was Fair Oaks Station.