Palo Alto Battlefield National Historical Park near Brownsville, Texas, United States, is a National Park Service unit which preserves the grounds of the May 8, 1846, Battle of Palo Alto. It was the first major conflict in a border dispute that soon precipitated the Mexican–American War. The United States Army victory here made the invasion of Mexico possible. The historic site portrays the battle and the war, and its causes and consequences, from the perspectives of both the United States and Mexico.