The offensive began on October 10 when Stuart led a diversionary attack on Brig. Gen. George A. Custer's division holding the Robinson River west of Culpeper Courthouse. This movement convinced Meade that Lee did not intend to fall back toward Richmond, and Meade moved back on Rappahannock Station to counter Lee's movement. On October 12 Confederate infantry were spotted at Amissville, convincing Meade that Lee planned to send his army through Thoroughfare Gap as he had in 1862. Accordingly, Meade retreated toward Centreville along the Orange and Alexandria Railroad to defend Washington from such a movement. Lee, however, intended to converge on Warrenton and stay to the south of the Bull Run Mountains. On October 13, Stuart was dispatched to reconnoiter the position of the Union left flank as it withdrew toward Centreville.