Green crossed Berwick Bay as fast as he could, and pushing on found the post at Bayou Ramos abandoned. The Union troops stationed there had retired to Bayou Boeuf, and so at daylight on the 24th, without feeling or firing a single shot, the united guards of the two stations, numbering 433 officers and men, with four guns, commanded by Lieutenant-Colonel Duganne, of the 176th New York, promptly surrendered to the first bold summons of a handful of Green's adventurous scouts riding five miles ahead of their column. Taylor now turned over the immediate command of the force to Mouton and hastened back to Alexandria to bring down Walker, in order to secure and extend his conquests. Mouton marched at once on Donaldsonville.
When the Union forces at La Fourche Crossing found the Confederates returning in such strength, they made haste to fall back on New Orleans, and were followed as far as Boutte Station by Waller's and Pyron's battalions.
On the 27th of June, Green, with his own brigade, Major's brigade, and Semmes's battery appeared before Donaldsonville, and demanded the surrender of the garrison of Fort Butler. This was a square redoubt, placed in the northern angle between the bayou and the Mississippi, designed to command and protect the river gateway to La Fourche, mounting four guns, and originally intended for a garrison of perhaps 600 men. The parapet was high and thick, like the levee, and was surrounded by a deep ditch, the flanks on the bayou and the river being further protected by stout stockades extending from the levees to the water, at ordinary stages. The work was now held by a mixed force of 180 men, comprising two small companies of the 28th Maine--F, Captain Edward B. Neal, and G, Captain Augustine Thompson,--besides a number of convalescents of various regiments. Major Joseph D. Bullen, of the 28th, was in command, and with him at the time was Major Henry M. Porter, of the 7th Vermont, provost-marshal of the parish of Iberville, whose quarters in the town on the other side of the bayou were no longer tenable.
Farragut, who had gone down to New Orleans and hoisted his flag on the _Pensacola_, leaving Palmer and Alden in command of the upper and lower fleets before Port Hudson, had disposed his gunboats so as to patrol the river in sections. The _Princess Royal_, Lieutenant-Commander M. B. Woolsey, was near Donaldsonville; the _Winona_, Lieutenant-Commander A. W. Weaver, near Plaquemine; and the _Kineo_, Lieutenant-Commander John Watters, between Bonnet Carré and the Red Church. As soon as the Confederates appeared before Donaldsonville, Woolsey was notified, and couriers were sent up and down the river to summon the _Winona_ and the _Kineo_.