... interval between McClellan's troops as the latter approached the Chickahominy, and, when he was fairly astride the little river, to attack him. He must do this before McDowell, moving southward from Fredericksburg , could swell the tide of battle against Richmond. On the morning of May 30th reconnoissances showed that one entire corps and a part, if not the whole, of another were on the south side of the rive...