The Texas annexation was the 1845 incorporation into the United States of America of the Republic of Texas, which was admitted to the Union as the 28th state.
The Battle of Pablo Alto, the first major engagement of the U.S.-Mexican War, was fought on May 8, 1846, just north of present-day Brownsville, Texas.
American forces under General Winfield Scott made the country's first amphibious landing at Vera Cruz, a Mexican coastal city, on March 9, 1847. Before the Mexican Army knew it, 12,000 American troops were on land and marching toward Vera Cruz.
On September 13, 1847, the American army assaulted the Mexican Military Academy, a fortress known as Chapultepec, which guarded the gates to Mexico City.