Following his withdrawal from Rocky Face Ridge, the first battle in Maj. Gen. William T. Sherman's campaign against Atlanta, Confederate Gen. Joseph E. Johnston established a four-mile defensive position protecting the Western & Atlantic Railroad west and north of Resaca, where the railroad crossed the Oostanaula River. On May 13th, Sherman tested the Rebel lines, sending forward divisions to skirmish with the Confederates, with little substantive result. On the 14th, the fighting erupted into a full-scale battle. Sherman attacked the Confederate center with John M. Schofield's Army of the Ohio, and Johnston replied with a counter-attack against the Union left with Maj. Gen. John B. Hood's corps. Neither attack was decisive. On the 15th, Sherman renewed his assault on the Confederate center, including a focused attack on the four guns of Confederate Captain Max Van Den Corput, placed forward of the line in an exposed position astride the Dalton Road. Meanwhile, Brig. Gen. Thomas Sweeny’s Sixteenth Corps division of Federal troops crossed the Oostanaula at Lay’s Ferry at the south end of the Confederate line, effectively flanking Johnston out of his entrenchments and forcing him to withdraw that evening. Sherman's overpowering advantage in manpower and his flanking technique would continue be used against Johnston repeatedly during the Atlanta campaign, usually with success.