Confronted by overwhelming numbers, Confederate forces fell back from Chancellorsville and established a defensive position here on April 30. General Robert E. Lee instructed Richard H. Anderson, who commanded this line, to set his spades to work as vigorously as possible, and with 9,100 men Anderson constructed a line of earthworks along Mine Road from U.S. Ford across Orange Turnpike and Orange Plank Road and then the crossed grade of the unfinished railroad to the south, covering all westerly approaches from Chancellorsville while he awaited reinforcements. In the early morning hours of May 1, General Lafayette McLaws’ division arrived to reinforce Anderson’s line, and before daylight three other divisions under Thomas “Stonewall” Jackson left Fredericksburg and began marching westward. At 8:30 am Jackson reached this advanced position, quickly surveyed the situation, and ordered Anderson and McLaws to put down their spades and pick up their rifles. With a combined force of 36,500, Jackson determined to strike the Union army before it attacked him, and at 10:30 am the signal was given for the Confederate columns to advance westward on the Turnpike and Plank Road. The opening clash of the Battle of Chancellorsville occurred shortly afterward in the woods and fields one mile ahead.