During the whole of the night of the 12th a dense fog prevailed, but this lifting about eight o'clock on the morning of Monday, the 13th of April, disclosed a day as bright and beautiful as the scene was fair. At an early hour the whole line advanced to within short musketry range, in substantially the same order as on the previous day. An attack by a detachment of Confederate cavalry upon the skirmishers of the 4th Wisconsin, in advance of the sugar-house, was easily thrown off, and a later demonstration by the Confederate infantry upon Paine's position in the grove shared the same fortune. Emory moved first the 8th New Hampshire, and afterwards the 133d and 173d New York, to the support of the 4th Wisconsin. At the same time Banks ordered Emory to send the other four regiments of Gooding's brigade and the two remaining sections of the 1st Maine battery to reinforce Bryan with the 175th New York on the left bank of the Teche, in order to be prepared, not only to meet a flank movement of the Confederates from that direction, but also to carry to works on that side, should this be thought best. After these dispositions had been completed the advance was steady and continuous, yet not rapid, until toward noon the last of the Confederates retired behind their breastworks and opened fire with musketry. The ditches already spoken of hindered the progress of the Union artillery, yet not seriously, while they afforded an excellent protection for the supports of the batteries and enabled the lines of infantry to rest at intervals: no small gain, for the sun grew very hot, and the march over the heavy windrows and across the deep ditches was exhausting. The Confederate gunboat _Diana_ took position well in front of the works, so as to command completely the right flank of Emory and Weitzel as they approached by a fire that, had it not been checked, must have enfiladed the whole line. Just as this fire was beginning to be disturbing it was silenced by a fortunate shot from one of the two 30-pounder Parrott guns, served by the 1st Indiana, posted in rear of Weitzel's left and trained upon the _Diana_, under the personal supervision of Arnold. The third shot from this battery, aimed at the flash of the _Diana_'s guns, exploded in her engine room; then above the trees, whose leafage full and low hid the vessel, was seen a flash like a puff of vapor; a rousing cheer was heard from the sharpshooters of the 4th Wisconsin and 8th New Hampshire, who had been told off to keep down the fire of the gunboat; and the _Diana_ was seen to pass up the bayou and out of the fight.