Chickering marched from Barré's Landing on the morning of the 21st of May. His force consisted of his own regiment, the 41st Massachusetts, commanded by Lieutenant-Colonel Sargent and mounted on prairie horses, the 52d Massachusetts, the 22d Maine, the 26th Maine, the 90th New York, the 114th New York, under Lieutenant-Colonel Per Lee, Company E of the 13th Connecticut, and Snow's section of Nims's battery.

The 90th New York, Colonel Joseph S. Morgan, was among the older regiments in the Department of the Gulf, having been mustered into the service in December, 1861. In January, 1862, it went to Florida with Brannan, on his appointment to command the Department of Key West; and in June, 1862, it formed the garrison of Fort Jefferson on the Dry Tortugas and of Key West; in November it was relieved by the 47th Pennsylvania, and joined Seymour's brigade on Port Royal Island, South Carolina. In March, 1863, it was back at Key West. There both regiments remained together until May. Meanwhile the district, then commanded by Woodbury, had been transferred from the Department of the South to the Department of the Gulf by orders from the War Office dated the 16th of March. These Banks received on the 10th of April, just before leaving Brashear, and as soon as he learned the condition and strength of the post, he called in the 90th New York. The regiment arrived at Barré's Landing just in time to go back to Brashear with Chickering. Morgan, though Chickering's senior in rank, waived his claim to the command and accepted a temporary brigade made up of all the infantry and the artillery.

The 114th New York, after quitting the column on the 19th of April, before passing the Vermilion, and performing the unpleasant duty of driving before it to Brashear all the beeves within its reach, was so unfortunate as to arrive at Cheneyville, on the return march, on the 12th of May, at the moment when Banks had made up his mind to retire to Brashear, and so just in time to face about and once more retrace its weary steps. Passing through Opelousas and Grand Couteau, the 114th turned to the left by the Bayou Fusilier and fell in with Chickering on the Teche.

The way was by the Teche, on either bank. By this time Mouton, reinforced by a brigade of three regiments under Pyron, with a light battery, probably Nichols's, had recrossed the Calcasieu under orders sent him by Kirby Smith on the 14th of May, before he knew of Banks's latest movement, and was approaching the Vermilion just in time to harry the flank and rear of Chickering's column, scattered as it was in the effort to guard the long train that stretched for eight miles over the prairies, with a motley band of 5,000 negroes, 2,000 horses, and 1,500 beeves for a cumbrous accompaniment. With the possible exception of the herd that set out to follow Sherman's march through Georgia, this was perhaps the most curious column ever put in motion since that which defiled after Noah into the ark.

On the 21st of May, Chickering halted near Breaux Bridge; on the 22d, above Saint Martinville; on the 23d, above New Iberia; on the 24th, at Jeannerette. On the following afternoon the column had halted five miles beyond Franklin, when a small force of the enemy, supposed to be part of Green's command or of Fournet's battalion, fell upon the rear-guard and a few shots were exchanged, with slight casualties on either side, save that Lieutenant Almon A. Wood, of the 110th New York, fell with a mortal wound. However, although the troops had already traversed twenty-five miles, this decided Morgan, who seems by this time to have taken the command, to push on, and the march being kept up throughout the night, the wearied troops, after a short rest for breakfast arrived at Berwick Bay at eleven o'clock on the following morning. In the last thirty-one hours the command had marched forty-eight miles. In the forty-one days that had passed since the campaign opened the 114th New York had covered a distance of almost 500 miles, nearly every mile of it afoot and with but three days' rest. The same afternoon the crossing began, and by the 28th every living thing was in safety at Brashear.

Banks had sent his despatches of the 13th of May to Grant by the hands of Dwight, with instructions to lay the whole case before Grant and to urge the view held by Banks with regard to the co-operation of the two armies. Dwight proceeded to Grand Gulf by steamboat, and thence riding forward, overtook Grant just in time to witness the battle of Champion's Hill on the 16th of May. That night he sent a despatch by way of Grand Gulf, promising to secure the desired co-operation, but urging Banks not to wait for it. The message arrived at headquarters at Simmes's plantation on the evening of the 17th, and was at once sent on to Brashear to be telegraphed to the commanding general at New Orleans. This assurance sent by Dwight really conveyed no more than his own opinion, but Banks read it as a promise from Grant, and once more convinced that it would be futile to attempt a movement toward Grand Gulf with the limited means of transport he had at hand, he again changed his plan and determined to go directly to Bayou Sara, hoping and trusting to meet there on the 25th of May a corps of 20,000 men from Grant's army.

The effective strength of the force now assembled near the head of the Atchafalaya was 8,400 infantry, 700 cavalry, 900 artillery; in all, 10,000. This great reduction was not wholly due to the effects of the climate, hardships, and long marches, but is partly to be ascribed to heavy detachments. These included the six regiments with Chickering, one at Butte-à-la-Rose, and one at Brashear.

At Simmesport the Corps sustained its first loss by expiration of service. The 6th New York, having completed the two years' term for which it had enlisted, went by the Atchafalaya and the railway to New Orleans, and there presently took transport for New York to be mustered out.

The movements of the army, though pressed as much as possible, were greatly retarded by the scanty means of water transportation and the pressing need of coal. From this cause the navy was also suffering, and urgent means had to be taken to supply the deficiency.

Reconnoissances, conducted by Lieutenant Harwood, in the course of which the enemy's cavalry was seen but not engaged, showed the roads from the Atchafalaya to Waterloo to be practicable for all arms. A detachment of cavalry sent out on the 18th to ascertain whether the Confederates had any force on the west bank of the Mississippi, encountered near Waterloo about 120 men of the 1st Alabama regiment, under Lieutenant-Colonel Locke, who had been sent over the day before from Port Hudson in skiffs to prevent any communication between the upper and the lower fleets. A skirmish followed, with slight loss on either side.