Question: Atchison County is named after a major general in the Missouri State Militia of what year?

Context paragraphs:
Atchison, Kansas: Atchison is a city and county seat of Atchison County, Kansas, United States, and situated along the Missouri River.  As of the 2010 census, its population was 11,021.  The city is named in honor of David Rice Atchison, United States senator from Missouri, and was the original eastern terminus of the Atchison, Topeka and Santa Fe Railway.  Atchison was the birthplace of aviator Amelia Earhart, and the Amelia Earhart Festival is held annually in July.  Atchison is also home of Benedictine College, a Catholic liberal-arts college.

Missouri Executive Order 44: Missouri Executive Order 44, also known as the Extermination Order, was an executive order issued on October 27, 1838, by the Governor of Missouri, Lilburn Boggs.  The order was issued in the aftermath of the Battle of Crooked River, a clash between Latter-day Saints and a unit of the Missouri State Militia in northern Ray County, Missouri, during the 1838 Mormon War.  Claiming that Latter-day Saints had committed open and avowed defiance of the law and had made war upon the people of Missouri, Governor Boggs directed that "the Mormons must be treated as enemies, and must be exterminated or driven from the State if necessary for the public peace—their outrages are beyond all description".  The militia and other state authorities—General John B. Clark, among them—would use the executive order to expel the Mormons from their lands in the state following their capitulation, which in turn led to their subsequent migration to Nauvoo, Illinois.

Missouri State Militia (Union): The Missouri State Militia was a federally funded state militia organization of Missouri conceived in 1861 and beginning service in 1862 during the American Civil War.  It was a full-time force whose primary purpose was to conduct offensive operations against Confederate guerrillas and recruiters as well as oppose raids by regular Confederate forces.  The MSM at one time numbered more than 13,000 soldiers, but this force was reduced to 10,000 soldiers, by the United States government.

Enrolled Missouri Militia: The Enrolled Missouri Militia was a state militia organization of Missouri in 1862 during the American Civil War.  It was a part-time force whose primary purpose was to serve as garrison and infrastructure guards, both to augment the Unionist Missouri State Militia in defense versus raids and to free the Missouri State Militia for offensive operations versus Confederate guerrillas and recruiters.

David Rice Atchison: David Rice Atchison (August 11, 1807January 26, 1886) was a mid-19th century Democratic United States Senator from Missouri.  He served as President pro tempore of the United States Senate for six years.  Atchison served as a major general in the Missouri State Militia in 1838 during Missouri's Mormon War and as a Confederate brigadier general during the American Civil War under Major General Sterling Price in the Missouri Home Guard.  He is best known for the questionable claim that for one day (March 4, 1849) he may have been Acting President of the United States.  This belief, however, is dismissed by nearly all historians, scholars, and biographers.

Atchison County: Atchison County is the name of two counties in the United States, both named for Missouri Senator David Rice Atchison:

Atchison County Memorial Building: Atchison County Memorial Building is a historic building located at Rock Port, Atchison County, Missouri.  It was built in 1919, and is a two-story, Classical Revival style reinforced concrete building on a raised basement.  It measures approximately 107 feet deep and 63 feet wide.  The front facade features four fluted Doric order columns that support an entabulature and frieze.  It was built with support from the Missouri General Assembly to serve as a World War I memorial and a community centre.

Atchison County Historical Museum: Atchison County Historical Society Museum is a museum dedicated to preserving the history of Atchison County, Kansas.  Both the city of Atchison and Atchison County, Kansas are named after United States Senator and legendary "President for a day" David Rice Atchison.

5th Regiment, Arkansas State Troops: In the spring of 1861, as the secession crisis deepened, many additional volunteer companies were being formed in the Arkansas State Militia.  The Militia Law of Arkansas as published in 1860 provided for a two-tiered militia system.  Section one of the law made all able-bodied free white male inhabitants between the ages of 18 and 45 liable for service.  Section 57 of the Militia Act established the second tier of militia organization, the volunteer company.  The act allowed each county to raise up to four volunteer companies.  These volunteer companies were to be either infantry, riflemen, cavalry, or artillery.  While the volunteer companies were to be separate from the regular militia units, they remained under the supervision and authority of the local militia regimental commander, who was required to set the time and place of the election of officers for volunteer companies and certify their election to the governor.  Volunteer Companies were allowed to select and acquire their own uniforms and their officers were authorized to wear the uniform of the company.  While the standard militia units were organized into lettered companies organized roughly along township boundaries, volunteer companies usually adopted colorful names to set them apart.  One example of the volunteer militia company is the ""Bell Point Guards", which would eventually become Company G of the 5th Regiment, Arkansas State Troops.  The unit was originally organized and on July 10, 1860, in the 51st Regiment, Arkansas State Militia, of Sebastian County.  The unit was composed primarily of German immigrants from Sebastian County.

9th Missouri State Militia Cavalry: The 9th Missouri State Militia Cavalry, was a cavalry regiment that served as an element of the Union Army in the state of Missouri during the American Civil War.  Unlike Militia units in other states, the 9th Missouri State Militia Cavalry was a full-time military unit, permanently engaged in internal counter-insurgency and protection of the state of Missouri from invasion by conventional Confederate units.  The regiment was equipped and paid by the Federal government and was integrated into the Federal military structure in the Department of Missouri.  The 9th MSM Cavalry was one of Missouri's most successful counter-guerrilla units.

Supporting paragraphs: Atchison County David Rice Atchison
Answer: 1838