A Thunder of Cannon
Archeology of the Mexican-American War Battlefield of Palo Alto
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The Battle of Palo Alto, fought on May 8, 1846, was the first of many battles in the Mexican American War, termed by Mexico as the War of North American Intervention. Palo Alto bears historical and national significance for both countries in that it was the first battle of the war, initiating a chain of events changing the course of history of both nations. For Mexico, the battle meant the loss of sovereignty of its northern frontier, and eventual defeat meant losing approximately one-half of its country. Mexico's loss also resulted in decades of ensuing political turmoil within Mexico, as reflected by: the eventual end of the Santa Anna era; subjugation to the foreign emperor Maximilian; rebuilding of the country by Juarez; a long period of dictatorship under Díaz; and revolutions during the early twentieth century.

For the United States, the Mexican-American War occupies an ambiguous place in its national historical consciousness. Depending on the prevailing mood of intellectuals and historians, it was either denounced as a wicked war of aggression against a weaker neighbor or justified as an inevitable phase in the expansion of a vigorous nation. Perhaps because of this ambiguity, Americans are unclear as to the purpose of this war, and, consequently, there is relatively little interest in its events. This obscurity is undeserved since the Mexican-American War was an important episode in our military and general history. Regarding nineteenth century warfare, this conflict resulted in a number of military innovations and significant lessons in strategy. In the context of general history, the war was important because of its results—over one million square miles of territory were added to the United States. The acquisition of the new lands eventually strengthened the nation, but the immediate effect caused internal division and weakened the ties of union. The area secured from Mexico became a prize of contention between the North and the South, between the forces of slavery and antislavery, a struggle that led inexorably toward a greater conflict, the Civil War.

Park Purpose

To recognize both the significance of this battle and the Mexican-American War as a whole, Congress authorized the establishment of a park unit two miles north of the city limits of Brownsville, Texas (Figures 1 and 2). Palo Alto Battlefield National Historic Site (NHS) is the only unit in the National Park Service system providing preservation and interpretation of resources related to the Mexican-American War. The two Acts of Congress establishing and enlarging the Palo Alto Battlefield NHS address preservation and interpretation of its historic resources and set out requirements for management of the area. Congress authorized this in 1978 (P.L. 95-625) to "preserve and area of unique historical significance..." The authorization further required a feasibility study on the acquisition of additional, adjacent lands that would fully protect the historical integrity of the battlefield. Thus, the Palo Alto Battlefield NH Site Act of 1991 (P.L. 102-304) established a 3,400 acre site for the Palo Alto Battlefield NHS on June 23, 1992.

Figure 1. Regional map showing the location of Palo Alto Battlefield NHS in Texas.

Figure 2. Vicinity map showing the location of Palo Alto Battlefield NHS in South Texas. (click on image for a PDF version)

Section 3(a) of the above law further defined the purpose of this national historic site:

In order to preserve for the education, benefit, and inspiration of present and future generations the nationally significant site of the first battle of the Mexican-American War, and to provide for its interpretation in such a manner as to portray the political, diplomatic, military, and social causes and consequences, there is hereby established the Palo Alto Battlefield Historic Site... In furtherance of the purposes of this Act, the Secretary is authorized to enter into cooperative agreements with the United States of Mexico... and with owners of Mexican-American War properties within the United States of America for the purposes of conducting joint research and interpretive planning for the historic site and related Mexican-American War sites. Interpretive information and programs shall reflect historical data and perspectives of both countries and the series of events associated with the Mexican-American War.

The NPS includes archeological investigations as part of its development policy involving "studies, plans, and actions to accompany or precede park development, and to be part of a comprehensive planning sequence" (NPS 1980:1-3). A natural adjunct to the archeological study of Palo Alto is in-depth and ongoing historical research. Battlefield interpretation based on historical accuracy is essential not only to provide a sound plan for park management but also for addressing issues of cultural and national sensitivities. The park purpose requires "...its interpretation in such a manner as to portray the battle and the Mexican-American War and its related political, diplomatic, military, and social causes and consequences" (NPS 1992:2).

Archeological Investigations at Palo Alto

Archeologically productive sites are part of our common cultural heritage. Some sites are significant primarily on the local level, the integral parts of the history of a community; some reflect the roots of that community and the stages through which it evolved. Other sites are of statewide importance, reflecting trends and events that helped form the political, social and economic entity in which we live. Relatively few sites can be viewed as a part of our shared national heritage. Certainly, the event that took place at Palo Alto on May 8, 1846, meets all of the above levels of significance.

Until recently, battlefields were rarely investigated by an historical archeologist. Perhaps this bias against such investigation is partly based on the belief, once expressed by Nöel Hume (1969), that "little can usefully be said about battlefield sites.. [where]...the salvage of relics becomes the be all and end all". If, indeed, a battlefield is nothing but a repository of random, rusting relics, then avoidance by the serious researcher is probably correct. Implicit in this line of reasoning is the assumption that archived documents and various other historical records sufficiently meet the needs of the interested historian.

Since the 1980s, there has been an upsurge of interest in this formerly neglected field of archeological research. For example, noted issues of concern in a Society of Historical Archeology newsletter include: strategies for battlefields protection; a planned symposium dealing with combat sites; and a request for data on artifact distribution patterns on Civil War battlefields (SHA Newsletter 1993:16-18). Obviously, archeological investigations of battlefields can provide interpretative data unobtainable from documents.

As one might expect, participants in a battle can have different views and interpretations of the events and actions. Fortunately, these differing historical accounts of a battle, and the interpretations of these accounts by historians, can be regarded by the historical archeologist as sources of alternate hypotheses with archeological evidence used to test each alternative (Gould 1983:118). Nevertheless, for mutual checks and balances to exist between historical archeology and history, the archeologist must first create an objective approach for analysis of the physical remains.

The basis for all archeological investigations is the axiom that objects are deposited in recognizable and interpretable patterns. In their investigation of the Little Bighorn battlefield, Scott et al. (1989:8) shaped their research objectives on the principle that "there exists a behavioral relationship between historical events and the physical remains of events... Behavior on the battlefield can be understood by exposing these relationships and evaluating them in historical contexts". Historical issues of the events of the Little Bighorn fight provided direction for this research, with the researchers' overriding goal of understanding battle events as represented by the archeological record. Ancillary research objectives of Scott et al., such as identification of armaments, equipment and human remains, were generated to identify behavioral relationships. For example, Scott et al., using modern firearm identification analysis applied in crime labs, identified specific battle activity areas based on the variety of armaments used at that fight. These procedures identified firearm types by determining ammunition calibers, distinguishing marks on metal cartridge cases, bullets, and firearm parts. In contrast with the combatants at Little Bighorn, those who fought at Palo Alto almost exactly 30 years earlier possessed a fundamentally different armaments system. Both the Americans and Mexicans employed cannon, and their firearms required paper, not metal, cartridges. In addition, this type of armaments system required a set of tactics different than those used at Little Bighorn. Therefore, a concomitant difference in artifact patterning would occur. Nevertheless, a fundamental similarity exists in the underlying research framework employed for both projects, that is, the translation of artifact patterning into behavioral dynamics.

The overriding goal of the 1992-1993 Palo Alto battlefield investigations was to obtain enough archeological data to determine major battle line positions taken by the two opposing armies. Consequent investigative goals include:

1) a comprehensive search for and the study of pertinent historical documents, including battle maps, and published and unpublished eyewitness accounts. A synthesis of the data would be used for comparison with archeological data;

2) correlation of specific topographic features described at the time of battle with topographic features found on the battlefield today;

3) post-battle history of Palo Alto as it relates to topographic and artifact patterning modifications; and

4) detailed analyses of artifact types and patterns to provide a much-needed data base for future Mexican-American War studies. Notably, such analyses have some relevance for those investigating period battlefields associated with other wars.

Unfortunately, the process of degradation of this particular archeological resource began almost as soon as the smoke of battle cleared. Artifact removal accelerated during the last few decades, to the point where there was at one time a fear nothing of archeological value was left. We were pleasantly surprised to find this fear was unjustified. In fact, we now believe significant archeological information still survives, information that can fill in some of the blanks of history if retrieved under scientifically controlled conditions. Much may still be learned from the Palo Alto battlefield and, now that it is part of the NPS system, protection of this cultural resource is assured.

Two Notes of Consideration

1) This report follows Webster's New Universal Unabridged Dictionary, Second Edition, regarding usage of the word "army" in its capitalized and noncapitalized forms. When capitalized, "The Army" or "Regular Army" refers to a country's entire land forces organization of permanent, professionally trained troops. During the Mexican-American War, a period of national emergency for both Mexico and United States, the Regular Army of each country also included various units of semi- and nonprofessional citizen-soldiers. In noncapitalized form, "army" refers to a specific military unit, usually consisting of two or more subunits, together with auxiliary troops. This is a field army. For example, the Mexican army at the battle of Palo Alto consisted of four infantry regiments, supported by cavalry and engineer battalions, artillery batteries, nonprofessional irregulars, a field hospital and baggage train. A field army, therefore, is a subset of the Regular Army.

2) The English system of measurement is used since this system was predominant in nineteenth century United States. The nineteenth century Mexican linear unit of measurement, the vara, was variable in length but comparable to 2.8 ft. For this report, the vara has been converted to English measurement, allowing for comparisons and avoiding possible confusion. However, when dealing with analytical measurement of human bone, as is done in Appendix B, both English and metric systems are employed jointly.

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Last Updated: 25-Feb-2009