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

[31] fire of an hour and a half, all the rebel guns were silenced. The fort was surrendered while the troops were moving through the overflowed and almost impassable country to the position indicated. When they arrived at the rebel outworks in the rear, the enemy had already retreated towards Fort Donelson, on the Cumberland, and only a few men were captured in the fort. Pursuit failed to overtake them; but the most important success of opening the Tennessee was accomplished, and the gunboats went up the river, greatly to the terror of the rebel inhabitants of the interior of Tennessee.

But Grant, having taken the field, did not intend to content himself with the success so speedily achieved by the gunboats. He telegraphed to General Halleck, “Fort Henry is ours. . . . I shall take and destroy Fort Donelson on the 8th, and return to Fort Henry.” Nothing had been said before about a movement against Fort Donelson; and it is not unlikely that such a proposition might have prevented the attack on Fort Henry, or delayed it till the Union forces were still stronger, and the rebels were also reinforced. Hlalleck, however, did not object, and Grant forthwith made his preparations to bring up additional forces, and to lay his plans for a joint land and naval attack. Prompt in his decision, he was also prompt and vigorous in his movements.

The rapid rise of the waters of the Tennessee, and the absence of the gunboats up that river, delayed operations for some days; but Grant in the mean time exerted himself to bring up reinforcements, and to mature his preparations. General Halleck seconded