John:
The Blackwater was the line between Union occupied territory to the easst of the river and Confederate territory to the west, through much of 1863. BGEN Pryor's Virginia brigade had held that lien during the early part of the year. When Longstreet with the division of Hood and Pickett was detached from Lee's army in early March, it was first sent to Petersburg, but by the later part of March, units of the two divisions, followed by the whole force, were sent to the Balckwater. In early April the force crossed the river, and laid seige to Suffolk, but only to tie down Federal forces while Longstreet was gathering supplies. Probably as good a general treatment of this campaign, done in his as always readable style, is Shelby Foote's treatment of the Suffolk campaign in Volume II of The Civil War.

When Hooker crossed the Potomac, Longstreet was directed to raise the siege of Suffolk and come to Lee's assistance, which was done, but of course Pickett and Hood arrived too late to take part in the Chancellorsville campaign. Jenkins South Carolina brigade of five regiments, the Hampton Legion Infantry, the 1 S.C. (Hagood's), the 1 S. C. Rifles, and the 5th and 6th S.C., were left along the Blackwater, and there was sporadic skirmishing during May and June, always, if I am not incorrect, on the Suffolk side of the river. Although the Yankees substantially outnumbered Jenkins and a few Confederate cavalry units, the Federals were second rate troops who had seen almost no active field service, and they never did more than cause an occasional nuisance. I can get you the units which were at Franklin, if you give me a while to dig the data out. If I am not incorrect, Jenkins made his headquarters at Franklin or very close nearby.
Lee