The harvest of the guns.
From Brady Collection.

End of Invasion

Lee, as he looked over the desolate field of dead and wounded and the broken remnants of his once-powerful army still ready for renewed battle, must have realized that not only was Gettysburg lost, but that eventually it might all end this way. Meade did not counterattack, as expected. The following day, July 4, the two armies lay facing each other, exhausted and torn.

Late on the afternoon of July 4, Lee began an orderly retreat. The wagon train of wounded, 17 miles in length, guarded by Imboden's cavalry, started homeward through Greenwood and Greencastle. At night, the able-bodied men marched over the Hagerstown Road by way of Monterey Pass to the Potomac. Roads had become nearly impassable from the heavy rains that day, hindering the movements of both armies. Meade, realizing that the Confederate Army was actually retreating and not retiring to the mountain passes, sent detachments of cavalry and infantry in pursuit and ordered the mountain passes west of Frederick covered. Lee, having the advantage of the more direct route to the Potomac, reached the river several days ahead of his pursuers, but heavy rains had swollen the current and he could not cross. Meade arrived on the night of July 12 and prepared for a general attack. On the following night, however, the river receded and Lee crossed safely into Virginia. The Confederate Army, Meade's critics said, had been permitted to slip from the Union grasp.