Gen. McPherson’s men have succeeded in digging a mine underneath the defenses of Vicksburg. He will pack the mine full of black powder and explode it, hopefully blowing enough of a hole for us to attack. I wrote the other commanders to be prepared to exploit any advantage gained.
NEAR Vicksburg, June 25, 1863-12 m.
Major General F. J. HERRON:
One of our mines in General McPherson’s front will be exploded at 3 p. m. to-day. Have your rifle-pits well filled with men, and the remainder of your line, and when you hear the explosion open with all your artillery that is in position for FIFTEEN or twenty [minutes], and should you discover any signs of the enemy moving troops toward (the end) McPherson’s, you will make such demonstrations as to lead him to believe you intend to attack him.
U. S. GRANT.
The Papers of Ulysses S Grant, Vol 8, p 415
O.R., I, xxiv, part 3, p 441