Had Banks marched against Vicksburg at the same time that McClernand was moving on Little Rock, with Grant cut off somewhere in northern Mississippi, the Confederate commanders must have been dull and slow indeed had they failed to seize with promptitude so rare an opportunity for resuming, at a sweep, the complete mastery of the river, ruining their adversary's campaign, and eliminating 100,000 of his soldiers.
Thus, almost at the first step, the two great expeditions were brought to a standstill. They could neither act together nor advance separately. The generals began to look about them for a new way.
Since Port Hudson could neither be successfully attacked nor safely disregarded, the problem now presented to Banks was to find a way around the obstacle without sacrificing or putting in peril his communications. The Atchafalaya was the key to the puzzle, and to that quarter attention was early directed, yet for a long time the difficulties encountered in finding a way to the Atchafalaya seemed well-nigh insuperable. The rising waters were expected to render the largest of the bayous that connect the Atchafalaya and the Mississippi navigable for steamboats of small size and light draught. Of these there were, indeed, but few, so that the work of transporting troops from the one line to the other must have been, at the best, slow and tedious, yet, once accomplished, the army would have found itself, with the help of the navy, above and beyond Port Hudson, with a sufficient line of communications open to the rear, and the Mississippi and the Red River closed against the enemy.
The Confederates had in Western Louisiana, near the mouth of the Teche, a small division of Taylor's troops, about 4,500 strong, with one gunboat. At first Banks thought to leave a brigade, with two or three light-draught gunboats, on Berwick Bay to observe Taylor's force, and then to disregard it as a factor in the subsequent movements. This, while the Atchafalaya was high and the eastern lowlands of the Attakapas widely overflowed, might have been safely done, but all these plans were destined to be essentially modified by a series of unexpected events in widely different quarters.
In the second week of January, Weitzel heard that Taylor meditated an attack on the outlying force at Berwick Bay, and that with this view the armament of the gunboat _Cotton_ was being largely augmented. Weitzel resolved to strike the first blow. For this purpose he concentrated his whole force of seven regiments, including four of his own brigade, besides the 21st Indiana, 6th Michigan, and 23d Connecticut, with Carruth's and Thompson's batteries, four pieces of Bainbridge's battery, Barrett's Troop B of the Louisiana cavalry, and Company B of the 8th New Hampshire, commanded by Lieutenant Charles H. Camp. The 1st Louisiana held Donaldsonville and the 114th New York guarded the railway. To open the way, as well as to meet the fire of the _Cotton_, there were four gunboats of the light-draught flotilla under Buchanan--the flagship _Calhoun, Estrella, Kinsman,_ and _Diana_.