No. 1. Reports of Major General Nathaniel P. Banks, U. S. Army, commanding Department of the Gulf, with Return of Casualties.

No. 9.] HDQRS. DEPT. OF THE GULF, 19TH ARMY CORP Camp at Brashear City, La., April 10, 1863.

GENERAL: I left New Orleans on the 8th instant and established my headquarters at this point the same evening. Weitzel's brigade, of Augur's division, was already here, with three batteries and two sections of artillery, the siege train, and three companies of cavalry. Gover, excepting his cavalry, was then at Bayou boeuff station, on the railway, about 9 miles from here. Emory, exception one brigade and his cavalry and two batteries left at Baton Rouge, was at Bayou Ramas Station, which is about half way between Brashear and Bayou Boeuff. The remaining brigade of Emory's division and the transportation of both divisions were behind, moving up as rapidly as possible. The cavalry was en route from Baton Rouge.

Emory marched at 7 o'clock yesterday morning and reached here about 9. Weitzel began to cross the bay about 10, having first driven off a small part of the enemy, who from the opposite side were observing our movements. Emoury followed Weitzel closely. both divisions had crossed by dark; then absolutely by dark; then absolutely necessary transportation and supplies were sent over during the night and this morning. The limited amount of water transportation at our command made the crossing necessarily very slow.

Grover had marched from Bayou Boeuff at 9 a. m. and arrived here by 1 p. m. I had intended to place him on board the boats at night, so that he might leave at daylight and begin to land by 9 a. m., but this was impossible.

On Grand Lake, just beyond the head of Cypress Island, and within a few miles of each other, are two shell roads, leading from what the reported as good landings, a distance of 1 1/2 or 2 miles to the Bayou Teche. At one or the other of these landings I propose to disembark Grover, with the object of taking the enemy, who is at Pattersonville, in reserve and cutting off his retreat. The best pilots say that our steamers cannot come nearer than about 1 1/2 miles to the shore, and all our information confirms the truth of this. From that distance the disembarkation must be by the flats which we have collected and prepared for that purpose. Using all the expedition possible, Grover cannot reasonably be expected to land and take up position in less than twelve hours. The boats cannot run at night. His landing must necessarily take place by daylight. to insure this he must leave here by daybreak. The moment Grover passes Pattersonville with his fleet the enemy will certainly take the alarm, and if we let night interrupt the landing he will escape. We don not move against the enemy in front to-day, as I do not wish him to take the alarm any sooner than we can possibly help. We can whip him in any event, but if he stays where he is, and Grover gets into position before we attack in front, we shall destroy him. Everything promises success. Having destroyed the enemy's force and his salt-works at New Iberia, I propose, if time permits, to push a force as far as Opelousas.

Mr. Gabaudan, Rear-Admiral Farragut's secretary, arrived here this morning, having passed Port Hudson in a skiff and reached Baton Rouge on the 8th instant. For fear of accident no dispatches were sent by him, but he brought me verbal intelligence that he left the