William A. Crafts, Life of Ulysses S. Grant: His Boyhood, Campaigns, and Services, Military and Civil.

Halleck was soon after called to Washington as general-in-chief, and Grant resumed his former command; not, however, till Halleck had offered it to Colonel Robert Allen, a quartermaster, who had the good sense to decline it. Buell's army had already gone towards Chattanooga, and Grant's army was still further depleted by the departure of four divisions to reinforce the former. Grant was, therefore, compelled to act entirely on the defensive, an irksome duty for him; and his task was the difficult one of guarding several important points against an enemy who could readily concentrate at any one of them a force equal to his entire command. He strengthened the defences of Corinth, while he narrowly watched the threatening movements of the rebels, and proved himself active and prudent in a defensive campaign, though his genius was for offensive operations. He would have defeated the rebels at Iuka if his plans had been carried out; but Rosecrans, who commanded one of the columns moving against the enemy at that place, was slower than he promised to be, which caused a necessary detention of the other column, under Ord, and communication being difficult, the attacks were not well timed. The enemy effected his retreat by a road which Rosecrans was expressly ordered to hold, but which he failed to occupy.

Afterwards the rebels, combining their forces, attacked Corinth, to which place Grant had hurried Rosecrans, and made other provisions for its defence. With the aid of the strengthened fortifications Rosecrans