FE. J. Porter to George Cadwalader, June 15, 1861

Maj. Gen. GEORGE CADWALADER,

Commanding First Division, en route to Williamsport :

GENERAL: The commanding general desires you to give Captain Newton the necessary aid to carefully reconnoiter the position of the enemy beyond Williamsport, to ascertain if he is really vacating the borders of the Potomac in your vicinity. If he has vacated, the commanding general wishes you to throw a portion, if not the whole, of your division over the river, and send parts well in advance to secure against surprise, and, if it can safely be done, to annoy their retreat. Captain Newton will advise you of the wishes of the commanding general, and his advice you are desired to take into careful consideration for the purpose of acting upon. If you find the enemy gone, the general wishes General Wynkoop placed as soon as possible near the river, on your line, and General Williams advanced towards Shepherdstown.

very respectfully, your obedient servant,