In mid-June 1864, Grant abandoned his works at Cold Harbor and marched to Petersburg, a vital rail center. A mile south of here, at Wilcox Wharf (now Lawrence Lewis Jr. Park), steamboats ferried the troops and wagons of two corps across the James River on 14-15 June. Three miles downstream, at Weyanoke Point, Union engineers built a 700-yard-long pontoon bridge in seven hours on 14 June. For three days parts of two corps, as well as supply, ammunition, and ambulance wagons, crossed the bridge in a column 50 miles long. Engineers then dismantled the bridge. Grant's attack on the Confederate lines at Petersburg failed, and the armies settled into a ten-month siege.