The Invasion of Mexico (or Coalition-Mexican War) was a major military conflict between the Mexico and United States. The War began when Mexican Armed Forces attacked the Mexican-US border, killing 30 border patrol and National Guard on April 3, 2030. The United States Government issued a Ultimatum to Mexico demanding all soldiers who killed the patrols be handed over to US Authorities. The Mexican government refused. The United States declared war on Mexico and began the Invasion.