Their steady march took them to the valley floor later that day, but as they descended to the fields, villages, and lakes, the view that appeared enchanting from a distance slowly disappeared. Ballentine revised his description, remembering that “as we come closer its beauty vanishes. The lakes turn to marshes, the fields are not cultivated, the villages are mud, and the residents are wretched-looking Indian peons in rags and squalid misery.” This account is borne out by Captain William Lytle, who asserted that “the most magnificent sight in the world is to behold from a distance, a Mexican city. The immense number of domes and turrets rearing their lofty heads far above everything around them, makes the view most striking and picturesque.” However, on entering the cities, “how great the disappointment” to find yourself surrounded by unhappiness and misery.5
As they arrived in the valley, Scott sent out a detachment to purchase food, and because Noah Smith knew the surrounding area, he consented to Scott’s request to lead the expedition. Smith asserted that he could get all that the army needed. However, when he learned that he was to go out with Manuel Dominguez’s band of spies and cutthroats, he demurred. Not only did Smith fear for his own safety, but he also was certain that the “Forty Thieves,” as he called the spy company, would cause problems with the farmers and ranchers along the way. When he asked Scott for regular troops to accompany him, the general responded, “you shall have what you want,” and he sent Edwin Sumner’s dragoons along. At the hacienda of San Borke, the first place they came to, the residents told Smith that they were not afraid because they knew that the Americans protected individual rights and private property. The overseer, however, said that the owner was away and that he could not sell to the Americans for fear of retribution from the authorities. So Smith and the overseer had a private conversation wherein the two agreed that the army would take what it wanted by “force,” and later the proprietor could present a receipt at headquarters and receive compensation. The overseer then called together all the laborers and told them they would all be shot if they did not cooperate, thereby tricking them into loading supplies onto the pack mules that the Americans had brought. They left with barley, grain, and a hundred head of cattle.6
Meanwhile, the army arrived in echelon, and Scott sent out his engineers to gather information about the roads and terrain around Mexico City. Three large lakes covered much of the eastern side of the city—Texcoco, Chalco, and Xochimilco. The National Road, the main approach from the east, ran between Texcoco and Chalco, but the ground from the lakes to the city, a nine-mile stretch, was a marsh. Because this wet land extended from the east around to the southern side of the city, most of the roads were elevated causeways. An army approaching on the National Road would have to march along a raised roadbed, thus rendering itself vulnerable prey for an opposing force. In addition, Santa Anna had been busy fortifying a hill at the southern end of Lake Texcoco called El Peñon, where he intended to turn the Americans back. The alternatives to this route would take the army around the lakes to attack from either the north or south. To go north around the larger Lake Texcoco would greatly increase the distance for the army, and because a Mexican force was positioned at Texcoco blocking the road and because other fortified positions studded this route, Scott never seriously considered it. The other direction, south around the bottom of Lakes Chalco and Xochimilco, then turning right to approach the city from the south, provided a third option—the one he had already decided on before leaving Puebla.
By Thursday, August 12, five days after leaving Puebla, Twiggs’s division had marched straight across the intersection with the Texcoco Road and encamped in Ayotla on the north shore of Lake Chalco, where Scott established his headquarters. Quitman’s men set up camp just behind Twiggs, and Harney’s dragoons brushed back enemy pickets and took a position a mile and a half west of Ayotla. This gave the appearance that Scott intended to continue his advance along the National Road and approach the capital from the east, and that was just the impression that Scott wanted to give. However, he had already decided to take the southern approach, or the Chalco route. To that end, he ordered Worth, whose division was third in line of march, to turn left at the lake and set up camp at the town of Chalco with Pillow following him and posting his men nearby. Thus the two divisions at Ayotla would mask the real movement to the south, and Scott positioned his old friend to take the leading role. Worth was unaware of Scott’s intentions when he halted his division at Chalco.7
After receiving reports that the Chalco route might be impassable, Scott kept the army stationary in these locations for three days while his engineers gathered additional intelligence. As Robert Anderson put it, “Genl. Scott has his battle-fields well reconnoitred, and avails himself of all the advantages which science or skill may suggest.” The Chalco road south of the lakes had fallen into disuse since the early 1800s and was little more than a rough wagon trail, and Noah Smith had warned Scott that it traversed ravines and was not practical for an army.8 Santa Anna did not suspect that it could be used by the Americans, but for good measure, he had instructed that rocks be rolled onto it from the adjacent ridges and trees felled across it to impede an advance. This prompted the reports that Scott had received advising against this route, so he waited and rethought his options. After reconnoitering around Lake Chalco, Lee and Lieutenant Beauregard reported on the twelfth that the southern route would indeed pose difficulties but was passable. Before entirely ruling out an eastern approach, Scott sent his engineers out to gather every piece of information they could about the Mexican position at El Peñon.
U.S. Army’s advance on Mexico City. From Donald S. Frazier, ed., The United States and Mexico at War (New York: Macmillan, 1998). Reprinted by permission of The Gale Group.
Lee, along with Captain James L. Mason and Lieutenant Isaac I. Stevens, reported on its formidable defenses. Part of the lake wrapped around the front of El Peñon, giving the appearance that it rose up out of the water—indeed, Lee indicated that it “stands in the waters of Lake Tezcuco.” It was perhaps four hundred feet high and a thousand yards long, and its location adjacent to the road allowed it to completely dominate an approach from that direction. The hill had three levels or plateaus, each with breastworks, and Santa Anna had interspersed thirty pieces of artillery among the fortifications. On the causeway and four hundred yards in front of El Peñon was another battery. In addition to posting seven thousand defenders on the hill, Santa Anna had made his headquarters there, as he deemed this to be Scott’s most likely approach. Clearly, Santa Anna intended to make his stand here, and he had rallied his army and focused his people’s attention to defending the capital at this spot. And it was a good one. The water and marsh that surrounded it made a flank attack impossible. To approach from the east, the Americans would have to attack El Peñon straight on and take it at the point of the bayonet—a bloody proposition.9
Scott had an important decision to make. Captain Joseph R. Smith of Twiggs’s division recorded in his diary, “I know not what our great general will decide upon. He is most prudent and will not sacrifice a life if he can avoid it.” But an attack on El Peñon would come with a heavy sacrifice—perhaps 1,500 men. Scott knew that he could not take such a risk with his limited numbers and the uncertainty of reinforcements. He also knew that even if he could capture El Peñon, he would have to fight another, perhaps more desperate, battle to seize the city, and he simply could not afford the kind of fight that an approach from the east would necessitate. Discretion had to dictate whatever strategy he devised, for his paramount concern had to be preserving his army. Santa Anna hoped that Scott would batter his army against his defensive works, but although Scott indeed was willing to use his army as a battering ram, he realized that he could take that chance only as a means of gaining entry into the city itself.10
If El Peñon could not be attacked in flank, could the entire position be turned by swinging around it? To answer that question, he sent Lieutenants Beauregard and George McClellan, along with Mason
and Stevens, out to conduct reconnaissance in front of Mexicalzingo on August 13. If he could seize that town, he could bypass El Peñon entirely. Scott even accompanied this group part of the way, stopping at Chalco to consult with Worth. He told his division commander that he had reconnaissance parties out, and although he had not yet decided on a course of action, he would do so by August 15. He then instructed Worth to send out some of his own officers to examine the Chalco route. He remained at Worth’s headquarters an hour, and before leaving, he assured his division commander that he would be prudent and cautious in planning his advance on the city. “[I]f a place could be taken, it should be done with the minimum loss of life.” Scott told Worth that Scott would hold “himself responsible” for unnecessary casualties.11
Meanwhile, Beauregard and party found that Mexicalzingo was also well fortified and strongly defended by infantry and artillery, although it was not as strong a position as El Peñon. And like El Peñon, the surrounding water and wetland made the only practical approach along a raised causeway. Furthermore, the road leading to Mexicalzingo could be fired on by the guns atop El Peñon. However, they believed that the town’s location would make it more difficult for Santa Anna to reinforce. The Mexicalzingo option would also be difficult, but what appeared to trouble Scott most was that, like at El Peñon, if the position could be taken, the remaining distance to the city would be along an exposed causeway; thus the army’s location, after a potentially tough fight, would still be unfavorable. That fact notwithstanding, Scott was leaning toward the Mexicalzingo approach by the fourteenth.12
That afternoon, Colonel James Duncan, an artillery officer whom Worth had sent to scout the Chalco route, returned and reported that there were no enemy troops along the road and that with some work, the road was serviceable. Worth wrote a note recommending that approach, and he immediately sent it with Duncan to report to the commanding general at Ayotla. Duncan’s party went about as far as had Lee and Beauregard two days earlier, and they essentially confirmed what they had previously reported to Scott—that the road could be used, but with some difficulty. Scott had harbored misgivings about attacking Mexicalzingo all along and considered it the lesser of two evils. Duncan’s report prompted him to reconsider, and after doing so, he returned to his original plan. So on August 15, he ordered the army to march to San Agustin via the Chalco route, thus bypassing both El Peñon and Mexicalzingo. Unaware of Scott’s original plan, Worth and Duncan incorrectly assumed that Duncan’s findings had opened an entirely new possibility for the army. They concluded that the march to San Agustin resulted solely from their recommendations, and they felt slighted later when the commanding general’s official reports did not acknowledge their contribution. As it became clear that taking the southern approach was one of the decisive moves of the campaign, they adamantly sought to claim the credit. Duncan was quiet, obedient, and reliable, and many regarded him as one of the best artillerists in the army, but his reconnaissance, while important, did not add materially to what Scott already knew.13
Scott’s decision meant that he would be leaving fortified positions in his rear, which was a violation of the accepted mode of conducting a campaign. However, because Scott had cut off his own line of communication, he in effect had no rear to worry about. An earlier decision to maintain an open line back to the coast would have rendered this course of action inadvisable, if not impossible. He once again did the unexpected by shifting the battle front to an area that his opponent had not anticipated and had even believed to be impractical. In so doing, he turned two enemy positions by marching around them, “thus leaving the enemy to ruminate on the beauty of their works & the immense labour & expense it had cost them, without the pleasure of firing a gun.”14
On August 15, Worth’s division, followed by Pillow’s, led the way around the southern edge of Lakes Chalco and Xochimilco with the engineer company and a five-hundred-man work detail to clear the way. At the same time, Twiggs’s and Quitman’s divisions advanced from Ayotla toward El Peñon to mask the army’s true movement and hold Mexican troops east of the city. Next day, Twiggs and Quitman turned and followed the lead divisions along the Chalco route—a reversal that confused some of the volunteers. Such a sweeping flank march with his entire army would have violated one of Henri Jomini’s rules, except that the lakes offered an insurmountable barrier completely covering the American flank as it moved to the city’s south side. On the sixteenth and seventeenth, the army closed ranks in order to better protect the wagon train, but frequent delays in Pillow’s division proved annoying to the units behind it and made it impossible for it to remain close to those in its front. Despite Scott’s effort to tighten up his units, his army of almost 11,000 and its supply train of a thousand wagons stretched for twelve miles.15
The ruse did not last long. When a frustrated Santa Anna learned that the Americans were en route to San Agustin, he immediately began to shift units to the southwest. By the time Scott’s army began to arrive at the intersection where the Acapulco Road runs north to the capital, hundreds of Mexican laborers were busy with picks and shovels building fortifications west of Xochimilco. Anchored by the town of San Antonio, the enemy hastily built an impressive line of breastworks and gun emplacements that stretched across a two-mile-wide neck of flat land between the lake and a lava field. Called the Pedregal, this lava bed consisted of black, jagged rocks and crevices that extended for about three miles across. By Lieutenant William S. Walker’s account, it looked like “an ocean petrified in a storm.”16 This geographic anomaly could be traversed only with great difficulty on foot, and not at all on horseback or with artillery. It protected one of the Mexican flanks at San Antonio, while the lake shielded the other.
On Wednesday the eighteenth, Scott ordered Worth to turn his division at San Agustin and push north toward San Antonio to ascertain the enemy’s location and strength. With Edwin Sumner’s Second Dragoons leading the way, they pressed forward two miles along the Acapulco Road. “Grand” and “impressive” was the way one soldier described their march along the “beautiful avenue.” When ordered to halt, they knew they were close to San Antonio but could not yet see the town. Worth ordered his infantry to rest while the dragoons advanced to reconnoiter the Mexican line. Captain Seth B. Thornton was a member of Sumner’s unit, and he had been a participant in the war literally from the day it began. On April 25 of the previous year, he had led an American patrol into an ambush along the Rio Grande—the act that had precipitated the war. He was captured that day but later exchanged. On this day, Thornton rode forward with the dragoons to examine the enemy lines at San Antonio. He had ventured forward somewhat carelessly and was sitting with one leg over the pommel of his saddle when two heavy guns shattered the silence. An 18-pound shot struck him in the body, killing him instantly. The ball “tore him to pieces,” and as Lieutenant Ralph Kirkham put it, he “probably did not know what killed him.” According to Robert Anderson, the shot took “off his arm, and a good deal of his breast & side.” Comrades carried his “mutilated body” to the rear and buried him on the side of the road.17
Worth’s lead brigade immediately formed into battle line as a precaution despite being behind a cornfield and still unable to see anything. The other brigade remained on the road. When a group of skirmishers crept forward and peered out the other side of a cornfield, they were surprised at what they saw. Across a thousand yards of marsh, they saw a line of fieldworks running from building to building with sandbag parapets stacked on each roof. Thousands of soldiers and civilians were piling dirt here and carrying sandbags there to create a long line of connected forts that completely dominated the approach to the town. A large number of lancers sat on their mounts in the road watching the Americans. Now taking a more cautious approach, Worth sent engineers Mason, Stevens, Tower, and Smith forward to survey the enemy line. Mason crept forward to a nearby church, climbed up into the steeple, and looked in vain for a way to get around to the Mexican rear. All of the engineers came back and report
ed that the unusually strong position could not be flanked.18
While the engineers continued their dangerous work, Worth pulled the rest of his division back 1,500 yards and awaited orders. His men located a nearby hacienda that was both magnificent and deserted—just the right combination for curious and hungry soldiers. The hacienda was within sight and range of the Mexicans, who soon opened a sporadic fire on the Americans. The soldiers explored the estate but were careful to dodge or take cover in an effort to avoid the enemy shot and shells. “Keep one eye on the muzzles of the ‘big guns,’” the officers warned as the men roamed about. They quickly discovered that the establishment was a dairy farm owned by a wealthy Spaniard who had fled so quickly that “all the valuables were left behind.” William Austine recounted in a letter to his cousin how “we milked the cows and of course drank the milk for our services, and seriously thought of eating the animals themselves before quitting the premises.” The artillery fire continued throughout the day, and whenever one of the men, peering around the corner of a building at the enemy line, saw a puff of smoke belch from a cannon’s mouth, he would shout “jump” and everyone would take cover. Worth’s men held this position through the night.19
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