He did not participate in the Battle of Monterrey since his company was on detached duty from the regiment. John's major combat experience came at the Battle of Buena Vista. The Military History of Mississippi gives the following account of the battle:
" ••• They turned back sadly from what seemed the path of glory, unaware that they were destined to serv'e their country with almost unparalleled prominence on a battlefield that should be immortal in song and story. The Rifles encamped at Agua Nueva, eighteen miles from Saltillo, and were joined by some new regiments from Kentucky, Indiana, Illinois, and Arkansas under
General Wool. This was the composition ofTaylor's army, no seasoned troops but the Mississippians and two batteries of artillery, when the ablest Mexican General, Santa Anna, advanced with nearly three times as many men for the purpose of crushing Taylor and thus defeating Scott's plan of invasion. Taylor fell back toward Saltillo, and prepared to fight at the pass of La Angostura, a little south of the ranch called Buena Vista. The famous battle of February 22-23, 1847 was for the possession of this pass and the fighting was in a mountain valley ... The day seemed lost when Taylor arrived. He sent Davis with his eight companies to meet the enemy coming down the hillside. . . The Mississippians advanced through the demoralized commands that had yielded to the fierce attack, some of them practically destroyed, and on nearing the enemy formed in line of battle, advancing at double quick until in rifle range, then more slowly, firing as they advanced. . . The enemy in front fell back, but the Mexican cavalry circled to the rear of the Mississippians who found themselves alone in a perilous position. Colonel Davis then retired his regiment behind the ravine, where he was joined by Kilboum's battery and Lane's Indiana regiment. With this aid, the battle swung back and forth. Davis was greatly embarrassed by the lack of cavalry to meet the enemy's horsemen, which all the time menaced the flank of his line. Finally, in one of the retiring movements, a more formidable attack of cavalry was seen rapidly advancing from the flank of the position he had just fortunately abandoned. 'The
Mississippi regiment was filed to the right,' Colonel Davis wrote in his report, 'and fronted in line across the plain; the Indiana regiment was formed on the bank of the Ravine, in advance of our right flank, by which a re-entering angle was presented to the enemy ... The enemy, who was now seen to be a body of richly caparisoned lancers, came forward rapidly and in beautiful order, the files and ranks so closed as to look like a mass of men and horses. Perfect silence and the greatest steadiness prevailed in both lines of our troops as they stood at shouldered arms awaiting an attack. Confident of success and anxious to obtain the full advantage of a cross fire at a short distance, I repeatedly called to the men not to shoot. As the enemy approached, his speed regularly diminished until when, within eighty or one hundred yards, he had drawn up to a walk and seemed about to halt. A few files fired without orders and both lines then instantly poured in a volly so destructive that the mass yielded 'to the blow and the survivors fled. . . The second battle was at the place where the Mexican reserves made the last assault. . . the Mississippians coming up in time to pour a destructive fire into the right flank of the Mexican line. The enemy fled in confusion and the battle ended. . . In this last contest of the day my regiment equalled--it was not possible to exceed--my expectations,' Davis reported. 'Though worn down by many hours of fatigue and thirst, the ranks thinned by our heavy loss in the morning, they yet advanced upon the enemy with the alacrity and eagerness of men fresh to the combat.' ... Companies A and F, on detached duty during the battle ofMonterey, had the honor of first division in the battle of Buena Vista. . . The period of enlistment having expired, the First Regiment returned to the coast and sailed May 29,1847 for New Orleans, where it arrived June 9. When the regiment went to the war, its numbers aggregated, officers and men, 926. It brought back to New Orleans but 376... The regiment was welcomed with great enthusiasm at New Orleans."