By the evening of May 23, Lee finally understood that a major battle was developing in this location and began to plan his defensive position. He and his chief engineer devised a solution: a five-mile (8 km) line that formed an inverted "V" shape with its apex on the river at Ox Ford, the only defensible crossing in the area. On the western line of the V, reaching southwest to anchor on Little River, was the corps of A.P. Hill; on the east were Anderson and Ewell, extending through Hanover Junction and ending behind a swamp. Lee's men worked nonstop overnight to complete the fortifications. The new position represented a significant potential threat to Grant. By moving south of the river, Lee hoped that Grant would assume that he was retreating, leaving only a token force to prevent a crossing at Ox Ford. If Grant pursued, then Lee hoped the pointed wedge of the inverted V would split Grant's army and Lee could concentrate on interior lines to defeat one wing; the other Union wing would have to cross the North Anna twice to support the attacked wing.