That Lee’s study of the chances had not been patient and exhaustive it is impossible to doubt.  He was no hare-brained leader, but a profound thinker, following the highest principles of the military art.  That he had weighed the disconcerting effect which the sudden appearance of the victorious Jackson, with an army of unknown strength, would produce upon McClellan, goes without saying.  He had omitted no precaution to render the surprise complete, and although the defences of Richmond were still too weak to resist a resolute attack, Magruder, the same officer who had so successfully imposed upon McClellan at Yorktown, was such a master of artifice that, with 28,000 men and the reserve artillery,* (* Magruder’s division, 13,000; Huger’s division, 9000; reserve artillery, 3000; 5 regiments of cavalry, 2000.  Holmes’ division, 6500, was still retained on the south bank of the James.) he might be relied upon to hold Richmond until Porter had been disposed of.  The remainder of the army, 2000 of Stuart’s cavalry, the divisions of Longstreet and the two Hills, 35,000 men all told, crossing to the north bank of the Chickahominy and combining with the 18,500 under Jackson, would be sufficient to crush the Federal right.

The initial operations, however, were of a somewhat complicated nature.  Four bridges* (* Lee’s bridge, shown on the map, had either been destroyed or was not yet built.) crossed the river on Lee’s left.  A little more than a mile and a half from Mechanicsville Bridge, up stream, is Meadow Bridge, and five and a half miles further up is another passage at the Half Sink, afterwards called Winston’s Bridge.  Three and a half miles below Mechanicsville Bridge is New Bridge.  The northern approaches to Mechanicsville, Meadow, and New Bridge, were in possession of the Federals; and it was consequently no simple operation to transfer the troops before Richmond from one bank of the Chickahominy to the other.  Only Mechanicsville and Meadow Bridges could be used.  Winston’s Bridge was too far from Richmond, for, if Longstreet and the two Hills were to cross at that point, not only would Magruder be left without support during their march, but McClellan, warned by his scouts, would receive long notice of the intended blow and have ample time for preparation.  To surprise Porter, to give McClellan no time for reflection, and at the same time to gain a position which would bring the Confederates operating on the north bank into close and speedy communication with Magruder on the south, another point of passage must be chosen.  The position would be the one commanding New Bridge, for the Confederate earthworks, held by Magruder, ran due south from that point.  But Porter was already in possession of the coveted ground, with strong outposts at Mechanicsville.  To secure, then, the two centre bridges was the first object.  This, it was expected, would be achieved by the advance of the Valley army, aided by a brigade from the Half Sink, against the flank and rear of the Federals at Mechanicsville.  Then, as soon as the enemy fell back, Longstreet and the two Hills would cross the river by the Meadow and Mechanicsville Bridges, and strike Porter in front, while Jackson attacked his right.  A victory would place the Confederates in possession of New Bridge, and the troops north of the Chickahominy would be then in close communication with Magruder.