After the early morning of Sunday, the 12th of April, had been spent in light skirmishing and in demonstrations of the cavalry, designed to observe the enemy, and at the same time to attract and hold his attention, word came that Grover was under way. Banks knew that the passing fleet must soon be in plain sight of the Confederates. Therefore, it was now necessary to move promptly, and to feel the enemy strongly, yet not too strongly, lest he should abandon his position too soon and suddenly spoil all. From this moment it is important to remember that, save in the event of complete success, no word could come from Grover for nearly two days. The first news from him was expected to be the sound of his guns in the enemy's rear.
At eleven o'clock the bugle again sounded the advance. The whole line moved forward, continually skirmishing, until, about four o'clock in the afternoon, the infantry came under fire of the Confederate guns in position on the lines known as Camp Bisland. The line of march led up the right bank of the Atchafalaya until the mouth of the Teche was reached, thence up the Teche, partly astride the stream, yet mainly by the right bank. At first Weitzel formed on the right, Emory on the left, but as the great bend of the Teche was reached, about four miles below Bisland, and by the nature of the ground the front became narrowed at the same time that in following the change of direction of the bayou the line was brought to a wheel, Weitzel took ground to the left in two lines, while Emory advanced Paine's brigade into the front line on Weitzel's right, placed Ingraham in his second line, and made a third line with Godfrey.
Then finding the enemy beyond the Teche too strong for the cavalry to manage single-handed, Banks called on Emory to reinforce the right bank. Emory sent Bryan across with the 175th New York and a section of the 1st Maine battery, commanded by Lieutenant Eben D. Haley. They were to push the enemy back, and to conform to the advance of the main line.
The day was hot, the air close, and the march over the fields of young cane, across or aslant the heavy furrows and into and over the deep ditches, was trying to the men, as yet but little accustomed to marches. Fortunately, however, there was no need of pressing the advance until Grover's guns should be heard. About half-past five in the afternoon a brisk artillery fire began, and was kept up until night fell; then Emory moved the 4th Wisconsin forward to hold a grove in front of a sugar-house, near the bayou, well in advance of his right, in order to prevent the Confederates from occupying it, to the annoyance of the whole line.