May 8, 1846 - May 9, 1846
Fought on May 8-9, 1846 between U.S. troops led by General Zachary Taylor and the Mexican Army of the North under General Mariano Arista, the battles of Palo Alto and Resaca de la Palma were the first major engagements of the U.S.-Mexico War.
One week earlier, Taylor had moved the bulk of his army from Fort Texas, at the mouth of the Rio Grande opposite Matamoros, to Point Isabel, the U.S. Army's supply depot thirty miles away. The garrison at Fort Texas was soon besieged by Mexican forces and bombarded by Mexican artillery in Matamoros. To lift the siege, Taylor marched back to Fort Texas, encountering General Arista's army at Palo Alto, a watering hole a few miles outside of present-day Brownsville.
Though outnumbered, the U.S. Army enjoyed considerable advantages in terms of training, equipment and supplies. The use of so-called "flying artillery"—howitzers mounted on caissons that could be moved easily in the middle of the battle—proved decisive. Arista retreated, and the following day took up defensive positions a few miles away along a dry river bed known as Resaca de la Palma. A frontal assault drove the Mexican army back to Matamoros, lifting the siege of Fort Texas.