Southern Historical Society Papers, Volume 37.
Reverend J. William Jones, Ed.

The letter of the 23rd was written by General Lee after receiving two notes from General Stuart, which; no doubt stated in reply to his letter of the 22nd that General Hooker's army was still inactive, although Mosby did not so report to General Stuart until the next day. In it General Lee tells Stuart that Longstreet and Hill are moving to the Potomac; and Stuart chose the route via Seneca, with full knowledge that they were following Ewell.

According to the first order, Stuart was to cross the Potomac if Hooker's army was moving northward, and according to the second order he was to do so even if Hooker's army remained inactive. In his last order General Lee suggested that he cross the Potomac west of the Blue Ridge mountains ‘and move over to Fredericktown,’ which would place him on the right of Ewell; but discretion was allowed Stuart to cross east of the mountains if he could do so without hindrance. In either case, after crossing the Potomac, ‘he must feel the right of Ewell's troops, collecting information, provisions, etc.’ He was to be with Ewell on the march towards the Susquehanna and not merely to join him ‘on the Susquehanna.’

Of the movements of Longstreet and Hill while Hooker was still lying quiet south of the river, of which Stuart was advised as above stated, Col. Mosby says (page 103):