Why was Colonel Stephen Kearney important?

He led the US effort to capture New Mexico during the conflict with Mexico

He was well known for capturing the California Territory

He built the Santa Fe Trail to move into Texas

He assisted Mexico in defending new Mexico during the conflict with the US

Answer: He assisted Mexico in defending new mexico during the conflict with the US.

Explanation:

At the very onset of the Mexican-American war, Kearny was promoted to brigadier general on June 30, 1846 and took a force of about 2,500 to Santa fe, New Mexico. His Army of the west (1846) consist of 1600 men in the volunteer first and second Regiments of Fort Leavenworth, Missouri Mounted calvary regiment under Alexander Doniphan; an artillery and infantry Battalion; 300 of Kearny first US Dragoons and about 500 members of the Mormon Battalion. The Mexican military forces in new mexico retreated to Mexico without fighting and Kearny's forces easily took control of New Mexico