25th the Fourth Corps, was ordered to take up and fortify a position in the vicinity of the Seven Pines. The order was at once obeyed, a strong line of rifle-pits opened, and an abatis constructed a little in the rear of the point where the Nine-mile road comes into the Williamsburg road.
On the same day General Heintzelman was ordered to cross with his corps (the Third) and take a position 2 miles in advance of Bottom's Bridge, watching the crossing of White Oak Swamp, and covering the left and the rear of the left wing of the army. Being the senior officer on that side of the river, he was placed in command of both corps, and ordered to hold the Seven Pines at all hazards, but not to withdraw the troops from the crossings of White Oak Swamp unless in an emergency.
On the 28th General Keyes was ordered to advance Casey's division to Fair Oaks, on the Williamsburg road, some three-quarters of a mile in front of the Seven Pines, leaving General Couch's division at the line of rifle-pits. A new line of rifle-pits and a small redoubt for six field guns were commenced, and much of the timber in front of this line was felled on the two days following. The picket line was established, reaching from the Chickahominy to White Oak Swamp.
On the 30th General Heintzelman, representing that the advance had met with sharp opposition in taking up their position and that he considered the point a critical one, requested and obtained authority to make such dispositions of his troops as he saw fit to meet the emergency. He immediately advanced two brigades of Kearny's division about the fourth of a mile in front of Savage Station, thus placing them within supporting distance of Casey's division, which held the advance of the Fourth Corps.
On the 30th the troops on the sough side of the Chickahominy were in position as follows: Casey's division on the right of the Williamsburg road, at right angles to it; the center at Fair Oaks; Couch's division at the Seven Pines; Kearny's division on the railroad from near Savage Station toward the bridge; Hooker's division on the borders of White Oak Swamp. Constant skirmishing had been kept up between our pickets and those of the enemy. While these lines were being taken up and strengthened large bodies of Confederate troops were seen immediately to the front and right of Casey's position.
During the day and night of the 30th of May a very violent storm occurred; the rain, falling in torrents, rendered work on the rifle pits and brigades impracticable, made the roads almost impassable, and threatened the destruction of the bridges over the Chickahominy.
The enemy, perceiving the unfavorable position in which we were placed and the possibility of destroying that part of our army which was apparently cut off from the main body by the rapidly-rising stream, threw an overwhelming force (grand divisions of Generals D. H. Hill, Huger, Longstreet, and G. W. Smith) upon the position occupied by Casey's division.
It appears from the official reports of General Keyes and his subordinate commanders that at 10 o'clock a.m. on the 31st of May an aide-de-camp of General J. E. Johnston was captured by General Naglee's pickets. But little information as to the movements of the enemy was obtained from him, but his presence so near our lines excited suspicion and caused increased vigilance, and the troops were ordered by General Keyes to be under arms at 11 o'clock. Between 11 and 12 o'clock it was reported to General Casey that the enemy were approaching in considerable force on the Williamsburg road. At this time Casey's