Johnston's River Line was a Confederate defensive system built in June and early July 1864 along the northwest bank of the Chattahoochee west of Atlanta, through Mableton, Smyrna, and Vinings. Conceived by Brigadier General Francis A. Shoup and constructed by convalescing soldiers and more than a thousand impressed slaves, it used thirty-six arrowhead-shaped forts linked by trenches and artillery positions to create interlocking fire. After Kennesaw Mountain, Confederate troops occupied the works, but William T. Sherman chose to outflank rather than assault them, forcing Johnston to abandon the line on July 9. Though much has been lost, surviving earthworks remain a notable example of Civil War field engineering.