SLOCUM AND HANCOCK REACH THE FIELD
Maj. Gen. Oliver O. Howard had ordered the First and Eleventh corps back to Cemetery Hill at 4:10 P.M.; by 4:30, he, General Doubleday, and their subordinates were rallying and deploying the retreating troops in order to make the hill secure against a Confederate attack. The hill and the stone walls that crossed it provided a strong position for its defenders, but it was defensible only so long as the enemy did not occupy Culp's Hill on its right and Cemetery Ridge to its left and rear. Should this happen, and should the enemy be able to hold his gains, the Union forces on Cemetery Hill would have to abandon their bastion and fight elsewhere some other day. Fortunately, while the Eleventh Corps manned Cemetery Hill itself, the First Corps would be able to begin the occupation of the flank positions. The two corps on the field, if attacked, could not hold their position for very long in the face of General Lee's larger and growing force. Hopefully, help for Howard would come in time; the Third Corps was marching toward Gettysburg from Emmitsburg, but it could not be expected for a while. The Twelfth Corps was much closer. How soon would it arrive?
General Slocum and his Twelfth Corps had reached the hamlet of Two Taverns on the Baltimore Pike, about four and a half miles southeast of Gettysburg, late on the morning of 1 July. They had marched only five miles from Littlestown, Pennsylvania, that morning in a leisurely fashion and, having reached their objective for the day, were looking forward to some rest. The Twelfth was the army's smallest corps; it numbered only about 9,000 officers and men for duty. Its five brigades were formed into two divisions, the First commanded by Brig. Gen. Alpheus S. Williams