Very early on the following morning, May 9, 1846, General Arista retired to a strong position at Resaca-de-la-Palma, where he received a re-enforcement of 2,000 infantry and "a strong body of cavalry". Having posted his troops with much care, he was attacked by the Americans about 2 o'clock p.m. All arms participated with credit as before, but the chief glory of that day was justly awarded to Captain May and his squadron of dragoons, who charged and captured the Mexican batteries, which were much more effectively handled than on the previous day. Though they could not hold the guns nor bring them away, yet they were silenced, the general in command of them was captured, and, upon the advance of the American line, the whole Mexican army took to flight and was never again assembled north of the Rio Grande. General Taylor reported:

"Perceiving that no decisive advantage could be gained until this artillery was silenced, I ordered Captain May to charge the batteries with his squadron of dragoons. This was gallantly and effectively executed; the enemy was driven from his guns, and General La Vega, who remained alone at one of the batteries, was taken prisoner. The squadron, which suffered much in this charge, not being immediately supported by the infantry, could not retain possession of the artillery taken, but it was completely silenced."

Captain Mansfield, with others, again distinguished himself in the reconnaissance before the attacks upon the works of Monterey and in the battle also.

Monterey
The Battle of Monterey consisted of a series of severe combats (mostly assaults on the enemy's works) extending over three days, September 21 to 23, inclusive. Here the foot troops won the prize for distinguished and effective work. General [William J.] Worth, with his division, had been ordered to seize the Saltillo road and to attack the forts to the west of Monterey and to prevent a concentration of forces against him. A strong demonstration by large detachments from the main body was made before the eastern front. This speedily developed into an assault upon the forts, fortified houses, and intrenchments in that locality.

After a hard fight the main body of the attacking force was repulsed with heavy loss, but two companies of the 1st Infantry under Captain [Electus] Backus had captured a solidly constructed building suitable for defense, and being encumbered with wounded, held their ground and did not retreat with their regiment. Being isolated, they were under a heavy fire from all sides, but by superior marksmanship they held their position with great tenacity and silenced most of the fire against them, including that of a light battery, which lost many cannoneers and retired. Soon after, the Americans assaulted a neighboring work called "Fort Teueria". The assaulting troops had already lost a third of their strength and were about to retreat when Captain Backus, having completed a change of position, opened so telling a fire on the rear of Fort Teueria that the enemy wavered, whereupon the assault was renewed with entire success. By this exploit the Americans secured a footing in the fortifications of the east side of Monterey.

During this time and later General [William J.] Worth's command executed four very gallant attacks against superior numbers in positions of great natural and artificial strength. Colonel Childs carried Independence Hill and the Bishop's Palace, Captain [Charles F.] Smith carried Federaci¢n Hill, and General [Persifor F.] Smith carried Fort Soldado. Each of these exploits deserves a full description, but, like many other glorious acts, can not be noticed here.

Many were justly complimented on their soldier-like deeds, but General Howard said:

"Capt. Electus Backus, of the 1st Infantry, with Mansfield, became the brilliant point in these operations."