Editing John C. Breckinridge (section)

==Mexican–American War==
[[File:John C. Breckinridge from Waveland Collection.jpg|thumb|right|alt=Black and white oval portrait of Breckinridge in blue U.S. Army uniform, young man in his 20s, dark hair|Breckinridge in an undated photo]]
A supporter of the Mexican–American War, Breckinridge sought appointment to the staff of Major General [[William Orlando Butler]], a prominent Kentucky Democrat, but Butler could only offer him an unpaid aide position and advised him to decline it.{{sfn|Heck|1976|p=20}} In July 1847, Breckinridge delivered an address at a mass military funeral in Frankfort to honor Kentuckians killed in the [[Battle of Buena Vista]]. The oration brought Whig Senator [[Henry Clay]] of Kentucky, whose [[Henry Clay Jr.|son]] was among the dead, to tears, and inspired [[Theodore O'Hara]] to write "[[Bivouac of the Dead]]".{{sfn|Klotter|1986|p=103}}

Breckinridge again applied for a military commission after [[William Owsley]], the governor of Kentucky, called for two additional regiments on August 31, 1847.{{sfn|Heck|1976|p=21}} Owsley's advisors encouraged the Whig governor to commission at least one Democrat, and Whig Senator John J. Crittenden supported Breckinridge's application.{{sfn|Davis|2010|p=34}} On September 6, 1847, Owsley appointed [[Manlius Valerius Thomson|Manlius V. Thomson]] as colonel, Thomas Crittenden as lieutenant colonel, and Breckinridge as [[Major (United States)|major]] of the Third Kentucky Infantry Regiment.{{sfn|Heck|1976|p=21}}{{sfn|Davis|2010|p=34}} The regiment left Kentucky on November 1 and reached [[Veracruz (city)|Vera Cruz]] by November 21.{{sfn|Heck|1976|p=22}} After a serious epidemic of ''la Vomito,'' or [[yellow fever]], broke out at Vera Cruz,<ref>{{cite web |url=http://www.montana.edu/historybug/mexwar.html |title=Yellow Fever and the Strategy of the Mexican-American War |last=Tschanz |first=David W. |publisher=Montana State University |access-date=June 10, 2017 |archive-date=May 1, 2017 |archive-url=https://web.archive.org/web/20170501111646/http://www.montana.edu/historybug/mexwar.html |url-status=live }}</ref> the regiment hurried to [[Mexico City]]. Reports indicate that Breckinridge walked all but two days of the journey, allowing weary soldiers to use his horse.{{sfn|Heck|1976|p=22}} When they reached Mexico City on December 18, the fighting was almost over; they participated in no combat and remained as an army of occupation until May 30, 1848.{{sfn|Heck|1976|p=22}}{{sfn|Sifakis|1988|p=71}}

In demand more for his legal expertise than his military training, he was named as assistant counsel for [[Gideon Johnson Pillow]] during a court of inquiry initiated against him by [[Winfield Scott]].{{sfn|Davis|2010|p=37}}{{sfn|Heck|1976|p=23}} Seeking to derail Scott's presidential ambitions, Pillow and his supporters composed and published letters that lauded Pillow, not Scott, for the American victories at [[Battle of Contreras|Contreras]] and [[Battle of Churubusco|Churubusco]]. To hide his involvement, Pillow convinced a subordinate to take credit for the letter he wrote. Breckinridge biographer [[William C. Davis (historian)|William C. Davis]] writes that it was "most unlikely" that Breckinridge knew the details of Pillow's intrigue.{{sfn|Davis|2010|p=38}} His role in the proceedings was limited to questioning a few witnesses; records show that Pillow represented himself during the court's proceedings.{{sfn|Heck|1976|p=23}}{{sfn|Davis|2010|p=38}}

Returning to [[Louisville, Kentucky|Louisville]] on July 16, the Third Kentucky mustered out on July 21.{{sfn|Davis|2010|p=30}} During their time in Mexico, over 100 members of the 1,000-man regiment died of illness.{{sfn|Klotter|1986|p=103}} Although he saw no combat, Breckinridge's military service proved an asset to his political prospects.{{sfn|Klotter|1986|p=103}}