The Mexican-American War was a conflict between the United States and Mexico that lasted from 1846 to 1848. It resulted in the United States acquiring land that later became all or parts of the states of California, Nevada, Utah, Arizona, New Mexico, Colorado and Wyoming. Determining the exact number of deaths that occurred during the war is difficult, but estimates range from around 13,000 to 25,000 total deaths. In this comprehensive 5000 word article, we will analyze the available data to determine the most accurate estimate of the death toll of the Mexican-American War.
The Challenge of Calculating Death Tolls in 19th Century Wars
Calculating casualties and death tolls for wars fought in the 19th century is inherently challenging for several reasons:
- Record keeping was not as thorough or organized as it is today
- Communications and reporting from the battlefield were slow and inconsistent
- Many deaths went unreported, both among soldiers and civilians
- Precise causes of death were often not tracked or recorded
- Census data and population records were limited
For these reasons, historians and researchers are forced to make educated guesses and extrapolations based on the limited data that does exist. There are often wide variations in estimates, reflecting both the uncertainty of the data and differing methodologies used.
Mexican Deaths in the Mexican-American War
On the Mexican side, most estimates put the number of combat deaths at around 5,000-7,000. However, tens of thousands of Mexican civilians also died either directly from violence or indirectly from the ensuing chaos and disease. Here is a summary of Mexican losses:
- At least 5,000 Mexican soldiers killed in combat
- Hundreds to thousands of pro-Mexican militia members killed
- 1,500 Mexicans executed by US forces after surrendering
- Over 25,000 Mexican civilians died during the US occupation of Mexican territory
This puts total direct Mexican deaths at over 30,000 from combat and immediate postwar violence. However, many tens of thousands more likely died from disease, starvation and displacement caused by the war, putting total Mexican deaths well over 50,000.
Challenges in Determining Mexican Deaths
The wide range in estimates of Mexican deaths highlights the challenges in obtaining accurate counts:
- The Mexican army did not keep thorough records of its dead and injured soldiers
- Civilian deaths went largely unreported, especially in remote areas
- Disease epidemics and food shortages disproportionately affected poorer civilians
- Smaller skirmishes likely resulted in uncounted deaths
- Mass graves made precise counts difficult
For these reasons, Mexican deaths are likely on the higher end of estimates, possibly exceeding 50,000 when non-combat deaths are included.
American Deaths in the Mexican-American War
Records of American deaths in the war are more thorough but still imperfect. Most estimates put the number of US combat deaths at between 1,700 – 2,000. Adding non-combat deaths and injuries gives an overall toll of 13,283.
- 1,733 US soldiers killed in combat
- 11,550 total US Army dead from all causes
- 1,721 US Marines, Navy and militia dead
- Around 500 civilian deaths on the US side
This gives us a total of approximately 13,300 American deaths from the Mexican-American War. The main causes included combat fatalities, illnesses such as yellow fever, accidents, and injuries unrelated to combat.
How US Death Records Were Kept
US Army records were more thorough than their Mexican counterparts:
- Enlistment records helped account for combat fatalities
- Pension records helped confirm deaths after the war
- Hospitals recorded deaths from illness and injury
- Eyewitness accounts described specific battles’ death tolls
While still incomplete, these records provide a reasonably accurate count of American deaths within a few hundred. Civilian deaths are more uncertain, but estimated based on contemporaneous accounts.
Total Deaths from the Mexican-American War
Combining the Mexican and American death tolls, most research puts the total deaths from the Mexican-American War between 25,000 – 30,000. However, it is important to remember that precise totals are impossible to confirm.
- At least 25,000 Mexican combatants and civilians died
- Approximately 13,000 American combatants and civilians died
- Total deaths: Between 25,000 – 30,000
This death toll made the Mexican conflict the deadliest of the 19th century American wars. It was several times more deadly for Mexicans than Americans, primarily due to civilian deaths. Next, we will examine the course of the war to understand the campaigns and battles that resulted in these casualties.
Overview of the Mexican-American War Battles and Campaigns
Lasting from 1846 to 1848, the Mexican-American War consisted of a series of US offensives to seize Mexican territory. Here is a brief overview of the major battles and campaigns:
- Siege of Fort Texas – May 1846, first battle of the war with heavy Mexican casualties
- Battle of Palo Alto – May 1846, US victory that drove Mexican forces south
- Battle of Resaca de la Palma – May 1846, decisive US victory leading to the capture of Matamoros
- Invasion of New Mexico – August 1846, US forces captured Santa Fe without much resistance
- Battle of Monterey – September 1846, major US victory capturing the city after house-to-house fighting
- Battle of Buena Vista – February 1847, US forces turned back a larger Mexican army
- Veracruz Campaign – March 1847, US captured the vital port city of Veracruz
- Mexico City Campaign – April to September 1847, US drove inland capturing Mexico City
These campaigns succeeded in occupying Mexico’s northern provinces and capturing its capital. Next we will look at death tolls from the major battles and sieges.
Deaths from Major Battles and Sieges
The bloodiest engagements of the Mexican-American War included:
|Battle or Campaign
|Battle of Monterey
|1,000 total (400 Mexican, 120 American)
|Battle of Buena Vista
|2,000 total (1,500 Mexican, 500 American)
|1,000 total (900 Mexican, 100 American)
|Mexico City Campaign
|3,700 total (3,500 Mexican, 200 American)
Although not every battle is listed here, this accounts for a large portion of the war’s casualties. Disease outbreaks also contributed heavily to the death toll following occupations.
Disease Epidemics During the Mexican-American War
Disease accounted for more casualties and deaths than combat in the Mexican-American War, especially among civilians. Crowded conditions in occupied cities and camps led to outbreaks of deadly illnesses:
- Yellow fever – Mosquito-borne viral disease causing high fever and organ failure. Killed thousands of American troops.
- Malaria – Parasitic illness transmitted by mosquitoes. Afflicted thousands of soldiers and civilians.
- Dysentery – Intestinal infection that spreads rapidly in unsanitary conditions. Major cause of death among civilians.
- Typhus – Rickettsial infection spread by lice. Thrived in crowded refugee camps.
These diseases and others exploited the poor sanitation, lack of supplies, and inadequate medical care in occupied zones. Preventing disease was beyond 19th century medicine, contributing to the war’s severe mortality.
American Troops and Disease Mortality
Disease wreaked havoc on American troops as volunteers signed up ill-prepared for illness:
- Over 10,000 American soldiers died from disease, compared to 1,700 combat deaths
- Yellow fever caused over 7,000 American deaths alone
- Thousands more were disabled or discharged due to illness
- Many regular troops developed immunity, but fresh volunteers did not
Proper medical staffing, quarantines, and sanitation precautions may have reduced this toll. But 19th century medicine still struggled to manage epidemics or treat infections.
Civilian Fatalities from Disease and Starvation
Among civilians, disease deaths are harder to quantify but certainly numbered in the tens of thousands:
- Food shortages and displacement fostered malnutrition and starvation
- Mexico lacked facilities and staff to handle mass epidemics and refugees
- Dysentery, typhus, malaria and other diseases ravaged occupied zones
- Remote villages were especially hard hit without access to aid or information
These non-combat deaths were concentrated among the poor and vulnerable. They demonstrate the indirect costs of warfare even beyond the battlefield.
Legacy of the Mexican-American War’s Death Toll
The total human cost of the Mexican-American War extended far beyond combat casualties:
- At least 25,000 Mexican deaths – combat, civilian, disease, starvation
- Around 13,300 American deaths
- Heavy casualties among women, children, the poor and indigenous
- Widespread dislocation, displacement, and destruction of farms and villages
This deadly toll generated lasting resentment in Mexico and controversy in the US. However, it succeeded in transferring half of Mexico’s territory to the US. The war marked an influential chapter in the histories of both nations.
Impact on Mexico
For Mexico, the costs of the war were enormous both materially and demographically:
- Mexico lost half its national territory and important natural resources
- The death toll was equivalent to 2.5% of Mexico’s entire population
- Defeat discredited the Mexican political system and the military
- Mexico plunged into political instability and further foreign interventions
This disastrous outcome shook Mexico at a formative period following independence. The deep losses drove political tensions leading to the Mexican Revolution decades later.
Impact on the United States
For the US, the Mexican-American War had mixed legacies:
- Fulfilled the goal of securing vast western lands for American settlement
- Exposed logistical challenges in supplying and reinforcing distant armies
- Debate over the justice of the war and its expansionist aims increased sectional divides
- Battlefield experience trained future Civil War officers including Grant and Lee
Strategically, the US achieved its objectives. But the human cost was controversial, and the war amplified simmering political disagreements over slavery that soon boiled over.
Quantifying the loss of life in the Mexican-American War is a difficult historical challenge due to limited records. But most research concludes that approximately 25,000-30,000 people died over the course of the conflict. This devastating toll resulted from combat, disease, turmoil, and the chaos of war. The war’s outcome transformed North America, but at a steep human price that affected both victors and vanquished for decades to come.