Mapping the movements of the Federal II Corps between the repulse of Barlow's division by Barringer's North Carolina cavalry brigade on June 21 and the end of II Corps' counterattacks to recover its lost guns and lines on June 22 is proving one of the most difficult tasks I have ever faced even with the help of a lifelong student of the battle such as Don Lauter, who has studied the fight for 50 years. (I'm a newcomer, having studied the struggle for only about 30.)
There are a number of maps that help one understand II Corps' position just before its rout on June 22. The first comes from the Library of Congress and depicts the Federal line on or about June 21. (I'll explain the "on or about" below.)
The important part of the aforesaid map is in the lower center, where the blue line depicting the Federal position diverges and rejoins. I interpret the line on the right as the position at which II Corps arrived on the afternoon of June 21 and the line to the left as the line Pierce's and O'Brien's brigades of Gibbon's division of II Corps occupied around 3 a.m. on June 22. Hence the "on or about"
The next map is from the Official Atlas, Plate 64, No. 1. It depicts the Federal lines on Jerusalem Plank Road around August 1864. Major Duane of the Army of the Potomac's engineers drew the map for the Burnside court martial. It gives a more detailed picture of the lines than the June 21 map.
The first important line on the map above runs from southwest to northeast and enters Jerusalem Plank Road just north of Fort Davis. To its left is the line occupied by the main bodies of Pierce's and O'Brien's brigades of Gibbon's division and the 12th New York Battery at 3 a.m. on June 22. The upper part of the line still farther to the left was held by the pickets of Pierce's and O'Brien's brigades.
The next important map bears on the disposition of Mott's II Corps division, two brigades of which were brought up regiment by regiment on the left (west) of Gibbon's division on an east-west rather than a north-south axis beginning at 4:50 a.m. on June 22. Major John Willian, the author of the map, belonged to Mott's staff and had led one of the two advancing brigades on June 16. I bought his map at auction a few years ago and have made it available to anyone who wants to study it.