informing him that unless prevented Rosecrans would retreat, and
advising peremptory orders against his doing so.

As stated before, after the fall of Vicksburg I urged strongly upon the
government the propriety of a movement against Mobile. General
Rosecrans had been at Murfreesboro', Tennessee, with a large and
well-equipped army from early in the year 1863, with Bragg confronting
him with a force quite equal to his own at first, considering it was on
the defensive. But after the investment of Vicksburg Bragg's army was
largely depleted to strengthen Johnston, in Mississippi, who was being
reinforced to raise the siege. I frequently wrote General Halleck
suggesting that Rosecrans should move against Bragg. By so doing he
would either detain the latter's troops where they were or lay
Chattanooga open to capture. General Halleck strongly approved the
suggestion, and finally wrote me that he had repeatedly ordered
Rosecrans to advance, but that the latter had constantly failed to
comply with the order, and at last, after having held a council of war,
had replied in effect that it was a military maxim "not to fight two
decisive battles at the same time." If true, the maxim was not
applicable in this case. It would be bad to be defeated in two decisive
battles fought the same day, but it would not be bad to win them. I,
however, was fighting no battle, and the siege of Vicksburg had drawn
from Rosecrans' front so many of the enemy that his chances of victory
were much greater than they would be if he waited until the siege was
over, when these troops could be returned. Rosecrans was ordered to
move against the army that was detaching troops to raise the siege.
Finally he did move, on the 24th of June, but ten days afterwards
Vicksburg surrendered, and the troops sent from Bragg were free to
return.