Mexican-American War Timeline – 1846-1848

The Mexican-American War Timeline – 1846-1848 marks a period of intense conflict and territorial shifts between the United States and Mexico. This armed struggle, ignited by the 1845 U.S. annexation of Texas, dramatically reshaped the map of North America. The following timeline meticulously details the key events that unfolded during this pivotal era. The Mexican-American War Timeline – 1846-1848 highlights the battles, political maneuvers, and ultimately, the treaty that defined the outcome of the war.

1845

• December 29, 1845 – Annexation of Texas: Texas, formerly the Republic of Texas after its secession from Mexico in 1836, is officially annexed by the United States, becoming the 28th state. This act, viewed by Mexico as a hostile encroachment on its territory, served as a significant catalyst for the impending conflict.

1846

• January 1, 1846 – Polk’s Order to Taylor: President James K. Polk, a staunch advocate of westward expansion (Manifest Destiny), orders General Zachary Taylor to march his troops to the Rio Grande River. This action was ostensibly to protect Texas from potential Mexican incursions, but it also served as a provocation, positioning U.S. forces in a disputed zone claimed by both nations.
• April 25-26, 1846 – The Thornton Affair: In the contested territory north of the Rio Grande, a U.S. reconnaissance patrol led by Captain Seth Thornton is ambushed by Mexican forces. This incident, known as the Thornton Affair, resulted in American casualties and provided President Polk with the justification he needed to request a declaration of war from Congress. The Mexican-American War Timeline – 1846-1848 shows that this event was crucial for starting the conflict.
• May 3-9, 1846 – Siege of Fort Texas: Mexican forces lay siege to Fort Texas, a hastily constructed American fortification situated on the Rio Grande. Despite intense bombardment, the American garrison, under the command of Major Jacob Brown, withstands the siege. Major Brown was killed during the bombardment.
• May 8, 1846 – Battle of Palo Alto: General Zachary Taylor, leading a relief force, engages the Mexican Army under General Mariano Arista at Palo Alto, north of the Rio Grande. The battle, primarily an artillery duel, results in an American victory due to the superior range and accuracy of their cannons. The Mexican-American War Timeline – 1846-1848 shows that this was a significant early victory for the U.S. forces.
• May 9, 1846 – Battle of Resaca de la Palma: Just a day after Palo Alto, Taylor again confronts Arista at Resaca de la Palma, near present-day Brownsville, Texas. In a more decisive engagement, the American forces rout the Mexican army, further solidifying U.S. control of the disputed territory.
• May 13, 1846 – Congress Declares War: Following President Polk’s request and fueled by news of the Thornton Affair and the battles of Palo Alto and Resaca de la Palma, the U.S. Congress officially declares war on Mexico.
• May 18, 1846 – Occupation of Matamoros: U.S. troops, meeting with no resistance, occupy Matamoros, a key Mexican city across the Rio Grande from Brownsville. The occupation signifies the growing American presence on Mexican soil.
• July 4, 1846 – Fremont Declares California’s Independence: Captain John C. Fremont, leading a U.S. Army exploring expedition in California, proclaims the independence of California from Mexico. This marked the beginning of the "Bear Flag Revolt," a precursor to the full-scale American conquest of California.
• July 7, 1846 – Battle of Monterey (California): U.S. Navy Commodore John D. Sloat occupies Monterey, California, without significant resistance, marking another step in the American takeover of the region.
• July 8, 1846 – Seizure of Yerba Buena: Commodore John D. Sloat seizes Yerba Buena, which is modern-day San Francisco.
• July 14, 1846 – Occupation of Camargo: U.S. forces occupy Camargo, Tamaulipas, Mexico, further extending their control over northern Mexico.
• Early August 1846 – Battle of Cañoncito: General Stephen Watts Kearny defeats Mexican forces under Governor Manuel Armijo at Cañoncito, paving the way for the American occupation of Santa Fe.
• August 18, 1846 – Battle of Santa Fe: General Kearny occupies Santa Fe, New Mexico, without a major battle. Governor Armijo had dispersed his troops, effectively surrendering the city to the Americans.
• September 21-23, 1846 – Battle of Monterrey (Mexico): General Zachary Taylor captures the strategically important city of Monterrey in northeastern Mexico after a fierce three-day battle. Despite heavy casualties, the American forces prevail, but Taylor allows the defeated Mexican garrison to withdraw with their arms and equipment, a decision that draws criticism from Washington.
• September 22-30, 1846 – Siege of Los Angeles: Californios and Mexicans, led by General José María Flores, retake Los Angeles, demonstrating resistance to American occupation.
• September 26-27, 1846 – Battle of Chino: Californios defeat and capture a group of Americans hiding in an adobe house in Rancho Santa Ana del Chino.
• October 7, 1846 – Battle of Dominguez Rancho: Californios, led by José Antonio Carrillo, defeat U.S. Marines led by Captain William Mervine.
• October 24-26, 1846 – First Battle of Tabasco: Commodore Matthew Perry leads a naval demonstration against Tabasco, Mexico, resulting in an inconclusive outcome.
• November 14, 1846 – Occupation of Tampico: The U.S. Navy occupies Tampico, Tamaulipas, Mexico, a significant port city on the Gulf Coast.
• November 16, 1846 – Battle of Natividad: A skirmish in the Salinas Valley in northern California results in an American victory. Also, the U.S. Army occupies Saltillo, Coahuila, Mexico.
• December 6, 1846 – Battle of San Pasqual: Californeros and Presidial Lancers defeat General Kearny’s forces in a bloody battle near San Diego, highlighting the continued resistance to American control in California.
• December 16, 1846 – Mormon Battalion Captures Tucson: The Mormon Battalion, a volunteer unit of the U.S. Army, captures Tucson, Sonora, with minimal resistance.
• December 25, 1846 – Battle of El Brazito: U.S. forces under Colonel Alexander Doniphan defeat a Mexican force at El Brazito, New Mexico, securing American control of the region.

1847

• January 2, 1847 – Battle of Santa Clara: Fought in California, resulting in a U.S. victory.
• January 8, 1847 – Battle of Rio San Gabriel: As part of a series of battles to control Los Angeles, the skirmish results in an American victory.
• January 9, 1847 – Battle of La Mesa: The last conflict before U.S. forces enter Los Angeles results in a U.S. victory.
• January 24, 1847 – Battle of Canada and First Battle of Mora: General Sterling Price defeats insurgents in New Mexico. Also, the First Battle of Mora is a failed attack by American Forces on Mora, New Mexico.
• January 29, 1847 – Battle of Embudo Pass: The last insurgent stand before the Siege of Pueblo de Taos in New Mexico resulted in an American victory.
• February 1, 1847 – Second Battle of Mora: Another American expedition armed with howitzers succeeded in razing the village of Mora, New Mexico.
• February 3-4, 1847 – Siege of Pueblo de Taos: Rancheros and Mexican Militia surrender to U.S. forces, thus ending the Taos Revolt.
• February 22-23, 1847 – Battle of Buena Vista: General Zachary Taylor, despite being heavily outnumbered, decisively defeats General Antonio López de Santa Anna at Buena Vista, south of Saltillo. This victory elevates Taylor to national hero status and significantly impacts his political prospects. The Mexican-American War Timeline – 1846-1848 indicates the importance of this battle.
• February 28, 1847 – Battle of the Sacramento: Colonel Alexander Doniphan defeats a larger Mexican army near the Sacramento River before capturing Chihuahua, Mexico.
• March 9 – 29, 1847 – Siege of Veracruz: U.S. forces, under General Winfield Scott, lay siege to the strategically vital port city of Veracruz. After a relentless bombardment, the city falls to the Americans, opening a pathway for an advance on Mexico City.
• April 18, 1847 – Battle of Cerro Gordo and First Battle of Tuxpan: General Winfield Scott’s U.S. troops flanked and drove Santa Anna’s larger Mexican army from a strong defensive position. Also, Commodore Matthew C. Perry seizes the port city of Tuxpan, Mexico.
• April 22, 1847 – Capture of Perote: 54 Guns and mortars and 500 muskets are captured at the Castle of Perote on the summit of the Eastern Cordilleras, 50 miles from Jalapa, Mexico.
• May 26, 1847 – Battle of Red River Canyon: New Mexican insurgents fight a skirmish with United States troops, resulting in an American victory.
• June 1847 – Second Battle of Tuxpan: Commodore Perry’s Mosquito Fleet engages Mexicans at Tuxpan for a second time resulting in a U.S. victory.
• June 16, 1847 – Second Battle of Tabasco: Commodore Perry captures Villahermosa, the last port city on the Mexican Gulf Coast.
• June 30, 1847 – Third Battle of Tuxpan: Perry’s Mosquito Fleet engages Mexicans for a third time, resulting in an American victory.
• July 6, 1847 – Battle of Las Vegas: New Mexican insurgents and United States soldiers fight at Las Vegas, New Mexico resulting in an American victory.
• July 9, 1847 – Battle of Cienega Creek: New Mexicans and United States forces clash near Taos, New Mexico Resulting in a U.S. victory.
• August 19, 1847 – Battle of Contreras: Santa Anna failed to support the Mexican line at a critical moment resulting in a U.S. victory.
• August 20, 1847 – Battle of Churubusco: Regular Mexican troops and Saint Patrick’s Battalion under Manuel Rincón hold a fortified monastery against General Winfield Scott.
• September 8, 1847 – Battle of Molino del Rey: In one of the bloodiest engagements of the war, the Americans suffer heavy casualties in capturing a suspected cannon foundry near Mexico City. Despite the losses, the battle results in an American victory.
• September 13, 1847 – Battle of Chapultepec: General Winfield Scott’s troops assault Chapultepec Castle west of Mexico City, resulting in a U.S. victory.
• September 13-14, 1847 – Battle for Mexico City: Fierce fighting takes place for Mexico City, resulting in an American victory.
• September 14, 1847 – Siege of Puebla: Mexican forces begin the siege of Puebla, Mexico.
• September 15, 1847 – Fall of Mexico City: Mexico City falls to American forces, marking a decisive turning point in the war.
• October 2, 1847 – Battle of Mulegé: A small detachment of American forces defeats Mexican forces led by Captain Manuel Pineda at Mulegé, Baja California Sur.
• October 9, 1847 – Battle of Huamantla: U.S. relief column can reach Puebla, Mexico.
• October 12, 1847 – Lifting of the Siege of Puebla: The Siege of Puebla was lifted by the relief force and could fight its way into the city.
• October 19, 1847 – Skirmish at Atlixco: This skirmish results in an inconclusive victory.
• October 31, 1847 – Bombardment of Punta Sombrero: The United States Navy schooner USS Libertad silences Mexican shore batteries in the Sea of Cortez.
• November 16-17, 1847 – Battle of La Paz: The Battle of La Paz, Mexico, results in a Mexican defeat.
• November 20-21, 1847 – Battle of San José del Cabo: Mexicans defeated by American forces at San Jose del Cabo, Mexico.
• November 27 – December 8, 1847 – Siege of La Paz: A second Mexican attack on La Paz, Mexico, ends in an American victory.

1848

• January 22 – February 14, 1848 – Siege of San José del Cabo: A failed Mexican siege of San Jose del Cabo.
• January – August 1848: Mexican partisans resisted the U.S. Army of Occupation.
• February 2, 1848 – Treaty of Guadalupe Hidalgo: The Treaty of Guadalupe Hidalgo is signed, officially ending the Mexican-American War Timeline – 1846-1848. Mexico cedes vast territories, including California, Nevada, Utah, and parts of Arizona, New Mexico, Colorado, and Wyoming, to the United States in exchange for $15 million.
• March 9 – 16, 1848 – Battle of Santa Cruz de Rosales: General Sterling Price advances into Chihuahua after the Treaty of Guadalupe Hidalgo was signed.

The Mexican-American War Timeline – 1846-1848 showcases a period of immense change for both nations, fundamentally altering their geographical boundaries and shaping their future relationship.