Editing Jefferson Davis (section)

==Mexican–American War==
[[File:Defeat of the Mexican Lancers by the Mississippi Rifles.jpg|thumb|upright=1.2|left|Watercolor of ''The Defeat of the Mexican Lancers by the [[Mississippi Rifles (Mexican–American War)|Mississippi Rifles]]'' by [[Samuel Chamberlain]] ({{circa}} 1860)|alt=Row of men on right with guns firing at men on horseback approaching on left]]
At the beginning of the [[Mexican–American War]], Mississippi raised a volunteer unit, the [[First Mississippi Regiment]], for the U.S. Army.{{sfn|Cooper|2000|p=124}} Davis expressed his interest in joining the regiment if he was elected its colonel, and in the second round of elections in June 1846 he was chosen.{{sfn|Eaton|1977|p=58}} He did not give up his position as a U.S. Representative, but left a letter of resignation with his brother Joseph to submit when he thought it was appropriate.{{sfn|Cooper|2000|p=130}}

Davis was able to get his regiment armed with new [[Percussion cap#Military firearms|percussion rifles]] instead of the [[smoothbore]] muskets used by other units. [[President Polk]] approved their purchase as a political favor in return for Davis marshalling enough votes to pass the [[Walker Tariff]].{{sfn|Dugard|2009|pp=153–157}} Because of its association with the regiment, the weapon became known as the "[[M1841 Mississippi Rifle|Mississippi rifle]]",{{sfn|Winders|2016|p=[{{Google Books|id=3hZDDQAAQBAJ|pg=PA13|plainurl=yes}} 13]}} and the regiment became known as the "[[155th Infantry Regiment (United States)|Mississippi Rifles]]".{{sfn|Dugard|2009|p=170}}

Davis's regiment was assigned to the army of his former father-in-law, Zachary Taylor, in northeastern Mexico. Davis distinguished himself at the [[Battle of Monterrey]] in September by leading a charge that took the fort of La Teneria.{{sfn|Dugard|2009|pp=205–208}} He then went on a two-month leave and returned to Mississippi, where he learned that Joseph had submitted Davis's resignation from the House of Representatives in October.{{sfn|Dugard|2009|pp=243–244}} Davis returned to Mexico and fought in the [[Battle of Buena Vista]] on February 22, 1847. He was wounded in the heel during the fighting,{{sfn|Dugard|2009|pp=282–284}} but his actions stopped an attack by the Mexican forces that threatened to collapse the American line.{{sfn|Lavender|1966|pp=199–203}} In May, Polk offered him a federal commission as a [[Brigadier general (United States)|brigadier general]]. Davis declined the appointment, arguing he could not directly command militia units because the [[U.S. Constitution]] gives the power of appointing militia officers to the states, not the federal government.{{sfn|Cooper|2000|pp=158–159}} Instead, he accepted an appointment by Mississippi governor [[Albert G. Brown]] to fill a vacancy in the U.S. Senate{{sfn|Davis|1991|p=164}} left when [[Jesse Speight]] died.{{sfn|Cooper|2000|p=160}}