The spark of the Mexican American war was when… General Taylor‘s troops crossed into Mexican territory, General Taylor attacked Mexico City, general Kearny attacked Santa fee, general Scott’s troops fired the first shots

General Taylor‘s troops crossed into Mexican territory

Explanation:

Zachary Taylor was in charge of the U.S. Army, experienced Soldier from the War of 1812. A U.S. Army came to the disputed territory in Texas to join Fort Texas. The first major battle took place before the outbreak of war at Fort Texas. The Americans numbered 2,500 and the Mexicans about 3,500.