There was a considerable delay at the mouth of the river, awaiting transports. The point of assemblage of the troops from New Orleans, Mobile, and Taylor’s army was Lobos Island, some three hundred miles south of the Rio Grande’s mouth. The march began January 9, 1847, but it was not until about February 12 that the first of the regulars sailed from the Rio Grande to Lobos Island. Scott had expected the concentration at Lobos to have been completed three weeks earlier. The fault was in the transport service.
The fleet did not leave Lobos Island until March 2. A week later a landing was effected near Vera Cruz, and on the 10th the first guns of the new campaign were heard,—shots from the castle of San Juan de Ulloa at Worth’s troops encamped upon the sand-hills. The investment of the city was speedily completed and siege operations begun. The army heard of Taylor’s remarkable victory at Buena Vista on the 15th of March. It took away their breath to learn that Santa Anna had marched a great army against Taylor after they had left, and had been defeated. It explained why there had been so little opposition to the landing of the American forces. Vera Cruz surrendered on the 29th.
Then the march into the interior of Mexico began, led by Twiggs’s division. The first objective point was Jalapa. Scott’s design was to get upon the mountain plateau before the yellow-fever season approached on the coast. It was deadly in that region. The precision with which Scott’s plans were carried forward, and their uniform success, made a profound impression upon the army. His reputation was very high before he had struck the first blow, but after Vera Cruz no one of that army doubted that he would soon enter the Mexican capital. The army’s morale was high from the outset; it was small, consequently but little bothered with the impedimenta which make the movements of a large army so slow and oftentimes tortuous. It marched rapidly, and Scott sent it square at the mark every time occasion offered.
Nevertheless there was great delay in the advance to the valley of Mexico. Operations were very energetic in the beginning. The battle of Cerro Gordo occurred on the 18th of April, where a complete and technically brilliant victory was won. It was here Santa Anna, already returned from his ill-fated movement against Taylor, undertook to defend the passage of the mountains against Scott’s advance. After careful reconnoissances, the American general turned his position, attacked his flank, and after a short fight broke up his army in utter rout, very nearly cutting off and capturing the whole. As it was, the Americans captured about four thousand prisoners, forty-three cannon, and three thousand five hundred small-arms. All this was done with a force of less than nine thousand Americans against some twelve thousand Mexicans strongly fortified.
This extraordinary victory opened the road to the valley. Thus within twenty days Scott had effected a landing, captured Vera Cruz, signally defeated the enemy in pitched battle, and taken the road into the heart of Mexico. Jalapa was entered on the 20th. At Jalapa seven regiments of volunteers were discharged, and the American force was too greatly reduced to attack the capital. The enforcements promised did not arrive. The advance, however, was pushed on to Puebla, a city then of some seventy thousand inhabitants, which was occupied by Worth on the 15th of May; Lieutenant Longstreet was with the division occupying Puebla. Here there was a long wait of weeks for the required forces to attack the capital, now less than three marches away. From Jalapa Scott set out for the front on May 23, arriving at Puebla on the 28th. Many of the higher officers rode out to meet and give the General a proper reception, and he entered the city in considerable state. “El Generalissimo! El Generalissimo!” was shouted by the citizens as the general-in-chief rode through the streets to his head-quarters. The army welcomed him with enthusiasm.
It was at the siege of Vera Cruz and the operations at Cerro Gordo that the engineer officers, R. E. Lee, G. B. McClellan, I. I. Stevens, G. T. Beauregard, and others, began to attract the notice of the line. Taylor had made little use of engineers in northern Mexico. He largely depended upon his own practised military eye to determine positions, either for the offensive or defensive. Scott’s methods were entirely different. He depended more upon reconnoissances led by his staff engineers, and their reports of situations, approaches, etc. He saw largely through the eyes of these officers, and his fine strategy was based on their information. Hence under Scott the engineer officers soon began to fill a large space in the eyes of the army. They became familiar figures.
Longstreet’s personal acquaintanceship with Lee began in this campaign. He was graduated from the Academy, No. 2 of the class of 1829, nine years before Longstreet entered it. Lee was already a captain of engineers when Longstreet entered as a cadet in 1838. He was past forty when the American forces landed before Vera Cruz. So in years he was much older, as in rank and prestige he was away above the line subalterns of that campaign, many of whom subsequently served under him and against him in 1861–65. He evinced great admiration, even reverence, for Scott’s generalship. In after-years his admirers claimed that much of Scott’s glory was due to Lee’s military ability. Scott gave him great praise. But while Lee was much respected in the army, it is due to say that nobody then ascribed the victories of American arms to him. Besides which, Colonel Joseph G. Totten was Scott’s chief-engineer, and Lee had another superior present in the person of Major J. L. Smith. The army thought General Scott entitled to the full credit of leadership in the campaign of 1847.
About August 14 sufficient reinforcements had arrived to warrant another forward movement. Scott had now about ten thousand men, with more coming on from the coast. His army was composed of four divisions, commanded by Generals Twiggs, Worth, Pillow, and Quitman, the two latter volunteer major-generals. The army began its final advance on the 8th of August, 1847. It had been idle nearly three months, awaiting the action of the government. It was General Longstreet’s opinion that with five thousand more men Scott could have followed Santa Anna straight into Mexico from Cerro Gordo. Owing to dilatoriness in raising troops at home, his active force at Puebla was at one time reduced to five thousand men. The three months’ halt gave the demoralized enemy time to recover courage and recruit their numbers.
The American advance from Puebla to the valley of Mexico was over the Rio Frio Mountain. The pass is over eleven thousand feet above the ocean. It was easily susceptible of successful defence, but the experience of the Mexicans at Cerro Gordo probably led their generals to conclude that Scott’s strategy was irresistible in a mountain region. At any rate there was no resistance, and after a toilsome climb of three days in the mountains, the Americans debouched into the beautiful valley without firing a shot.
This valley is one of the most singular of natural features. It is simply a basin in the mountains without any visible outlet. In seasons of heavy rainfall and snowfall on the stupendous mountains which surround it, the small lakes in this basin overflow, and sometimes inundate the capital itself. It is only in recent years that a channel, or tunnel, has been cut to drain off the superfluous water in time of need. At some time in the past the basin was probably a lake. There must have been some unknown subterranean outlet which originally drained it down and afterwards prevented it refilling. Before the artificial drain was made, however, there were indubitable signs that the lakes were much smaller than in the beginning of the sixteenth century when Cortés conquered the Aztec capital. The bed of this valley is seven thousand feet above the sea level. There are five shallow lakes in the basin. The capital is located on the west side of Lake Tezcuco. It contained about two hundred thousand people in 1847.