Stephen W . Kearny Stephen Watts Kearny ( ; surname also appears as Kearney in some historic sources ; August 30 , 1794October 31 , 1848 ) , was one of the foremost antebellum frontier officers of the United States Army . He is remembered for his significant contributions in the Mexican – American War , especially the conquest of California . The Kearny code , which was proclaimed on September 22 , 1846 in Santa Fe established the law and government of the newly acquired territory of New Mexico , was named after him . Biography . Early years . Kearny was born in Newark , New Jersey , the son of Philip Kearny , Sr . and Susanna Watts . His maternal grandparents were the wealthy merchant Robert Watts of New York and Mary Alexander , the daughter of Major General " Lord Stirling " William Alexander and Sarah " Lady Stirling " Livingston of American Revolutionary War fame . Stephen Watts Kearny went to public schools . After high school , he attended Columbia University in New York City for two years . He joined the New York Militia soon after he left school in 1812 , setting the course of the rest of his life . Marriage and family . In the late 1820s after his career was established , Kearny met , courted and married Mary Radford , the stepdaughter of William Clark of the Lewis and Clark Expedition . The couple had eleven children , of whom 6 died in childhood . Career . Kearny served as a First Lieutenant in the War of 1812 , and at the end of the war , he chose to remain in the US Army . He was assigned to the western frontier under command of Gen . Henry Atkinson . In 1819 , he was a member of the expedition to explore the Yellowstone River in present - day Montana and Wyoming . The 1819 expedition journeyed only as far as present - day Nebraska , where it established Cantonment Missouri , later renamed Fort Atkinson . Kearny was also on the 1825 expedition that reached the mouth of the Yellowstone River . During his travels , he kept extensive journals , including his interactions with Native Americans . In 1826 , Kearny was appointed as the first commander of the new Jefferson Barracks in Missouri south of St . Louis . While stationed there , he was often invited to the nearby city , the center of fur trade , economics and politics of the region . By way of Meriwether Lewis Clark , Sr . , he was invited as a guest of William Clark of the Lewis and Clark Expedition . During the 1830s , Kearny organized a regiment of dragoon s on the lines of a cavalry unit . The U . S . Cavalry eventually grew out of this regiment , earning Kearny his nickname as the " father of the United States Cavalry " . The regiment was stationed at Fort Leavenworth in present - day Kansas , and Kearny was promoted to the rank of Colonel . He was also made commander of the Army ' s Third Military Department , charged with protecting the frontier and preserving peace among the tribes of Native Americans on the Great Plains . By the early 1840s , when emigrants began traveling along the Oregon Trail , Kearny often ordered his men to escort the travelers across the plains to avoid attack by the Native Americans . The practice of the military ' s escorting settlers ' wagon trains would become official government policy in succeeding decades . To protect the emigrants , Kearny established a new post along Table Creek near present - day Nebraska City , Nebraska . The outpost was named Fort Kearny . However , the Army realized the site was not well - chosen , and the post was moved to the present location on the Platte River in central Nebraska . Mexican – American War ( 1846 – 1848 ) . At the outset of the Mexican – American War , Kearny took a force of about 2 , 500 men to Santa Fe , New Mexico . His Army of the West ( 1846 ) consisted of 1600 men in the volunteer First and Second Regiments of Fort Leavenworth , Missouri Mounted Cavalry regiment under Alexander Doniphan ; an artillery and infantry battalion ; 300 of Kearny ' s 1st U . S . Dragoons ( light cavalry ) 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 . Kearny established a joint civil and military government , appointing Charles Bent , a prominent Santa Fe Trail trader living in Taos , New Mexico as acting civil governor . He divided his forces into four commands : one , under Col . Sterling Price , appointed military governor , was to occupy and maintain order in New Mexico with his approximately 800 men ; a second group under Col . Alexander William Doniphan , with a little over 800 men was ordered to capture El Paso , in the state of Chihuahua , Mexico and then join up with General John E . Wool ; the third command of about 300 dragoon s mounted on mules , he led under his command to California along the Gila River trail . The Mormon Battalion , mostly marching on foot under Lt . Col . Philip St . George Cooke , was directed to follow Kearny with wagons to blaze a new southern wagon route to California . California . Kearny set out for California on September 25 , 1846 with a force of 300 men . En route he encountered Kit Carson , a scout of John C . Frémont ' s California Battalion , carrying messages back to Washington on the status of hostilities in California . Kearny learned that California was , at the time of Carson ' s last information , under American control of the marines and bluejacket sailors of Commodore Robert F . Stockton of the U . S . Navy ' s Pacific Squadron and Frémont ' s California Battalion . Kearny asked Carson to guide him back to California while he sent Carson ' s messages east with a different courier . Kearny sent 200 dragoons back to Santa Fe believing that California was secure . After traveling almost his weary 100 dragoons and most of his nearly worn - out mounts were replaced by untrained mules purchased from a mule herder ' s herd being driven to Santa Fe , New Mexico from California . On a trip across the Colorado Desert to San Diego Kearny encountered marine Major Archibald H . Gillespie and about 30 men with news of an on - going Californio revolt in Los Angeles . On a wet December 6 , 1846 day Kearny ' s forces encountered Andrés Pico ( Californio Governor Pio Pico ' s brother ) and a force of about 150 Californio Lancers . With most of his men mounted on weary untrained mules , his command executed an uncoordinated attack of Pico ' s force . They found most of their powder wet and pistols and carbines would not fire . They soon found their mules and cavalry sabers were poor defense against Californio Lancers mounted on well - trained horses . Kearny ' s column , along with the small force of Marines and volunteer militia , suffered defeat . About 18 men of Kearny ' s force were killed ; retreating to a hill top to dry their powder and treat their wounded , they were surrounded by Andre Pico ' s forces . Kearny was slightly wounded in this encounter , the Battle of San Pasqual . Kit Carson got through Pico ' s men and returned to San Diego . Commodore Stockton sent a combined force of U . S . Marine and U . S . Navy bluejacket sailors to relieve Kearny ' s column . The U . S . forces quickly drove out the Californios . In January 1847 a combined force of about 600 men consisting of Kearny ' s dragoons , Stockton ' s marines and sailors , and two companies of Frémont ' s California Battalion won the San Gabriel and the La Mesa and retook control of Los Angeles on January 10 , 1847 . The Californio forces in California capitulated on January 13 to Lt . Col . John C . Frémont and his California Battalion . The Treaty of Cahuenga ended the fighting of the Mexican – American War in Alta California on that date . Kearny and Stockton decided to accept the liberal terms offered by Frémont to terminate hostilities , despite Andre Pico ' s breaking his earlier , solemn pledge that he would not fight U . S . forces . As the ranking Army officer , Kearny claimed command of California at the end of hostilities despite the fact that California was brought under U . S . control by Commodore Stockton ' s Pacific Squadron ' s forces . This began an unfortunate rivalry with Stockton , whose rank was equivalent to a rear admiral ( lower half ) today . Stockton and Kearny had the same equivalent rank ( one star ) and unfortunately the War Department had not worked out a protocol for who would be in charge . Stockton seized on the treaty of capitulation and appointed Frémont military governor of California . In July 1846 , Col . Jonathan D . Stevenson of New York was asked to raise a volunteer regiment of 10 companies of 77 men each to go to California with the understanding that they would muster out and stay in California . They were designated the 1st Regiment of New York Volunteers and fought in the California Campaign and the Pacific Coast Campaign . In August 1846 and September the regiment trained and prepared for the trip to California . Three private merchant ships , " Thomas H Perkins " , " Loo Choo " and " Susan Drew " , were chartered , and the sloop was assigned convoy detail . On 26 September the four ships left New York for California . Fifty men who had been left behind for various reasons sailed on November 13 , 1846 on the small storeship . The " Susan Drew " and " Loo Choo " reached Valparaíso , Chile by January 20 , 1847 and after getting fresh supplies , water and wood were on their way again by January 23 . The " Perkins " did not stop until San Francisco , reaching port on March 6 , 1847 . The " Susan Drew " arrived on March 20 and the " Loo Choo " arrived on March 16 , 183 days after leaving New York . The " Brutus " finally arrived on April 17 . After desertions and deaths in transit the four ships brought 648 men to California . The companies were then deployed throughout Upper ( " Alta " ) and Lower ( " Baja " ) California from San Francisco to La Paz , Mexico . These troops finally allowed Kearny to assume command of California as ranking Army officer . The troops essentially took over all of the Pacific Squadron ' s on - shore military and garrison duties and the California Battalion and Mormon Battalion ' s garrison duties as well as some Baja California duties . With all these reinforcements in hand Kearny assumed command , appointed his own territorial military governor and ordered Frémont to resign and accompany him back to Fort Leavenworth , Kansas . On Kearny and Frémont ' s trip back east on the California Trail , accompanied by some members of the Mormon Battalion who had re - enlisted , they found and buried some of the Donner Party ' s remains on their trip over the Sierra Nevadas . Once at Fort Leavenworth , Frémont was restricted to barracks and ordered court - martialed for insubordination and willfully disregarding an order . A court martial convicted Frémont and ordered that he receive a dishonorable discharge , but President James K . Polk quickly commuted Frémont ' s sentence due to services he had rendered over his career . Frémont resigned his commission in disgust and settled in California . In 1847 Frémont purchased the Rancho Las Mariposas a large land grant in the foothills of the Sierra Nevada mountains near Yosemite , which proved to be rich in gold . Frémont was later elected one of the first U . S . senators from California and was the first presidential candidate of the new Republican Party in 1856 . Governorship and last years . Kearny remained military governor of California through August , when he traveled to Washington , D . C . and was welcomed as a hero . He was appointed governor of Veracruz , and later of Mexico City . He also received a brevet promotion to major general in September 1848 , over the heated opposition of Frémont ' s father - in - law , Senator Thomas Hart Benton . After contracting yellow fever in Veracruz , Kearny had to return to St . Louis . He died there in October at the age of 54 . He was buried in Bellefontaine Cemetery , now a National Historic Landmark in St . Louis . Legacy . Kearny is the namesake of Kearny , Arizona and Kearney , Nebraska . Many schools are named after Kearny , including Kearny Elementary in Santa Fe , New Mexico and Kearny High School in the San Diego neighborhood of Kearny Mesa . Kearny Street , in downtown San Francisco , is also named for him , as is a street within Fort Leavenworth , Kansas . Camp Kearny in San Diego , a U . S . military base which operated from 1917 to 1946 on the site of today ' s Marine Corps Air Station Miramar , was named in his honor . Fort Kearny in Nebraska is also named for him . His nephew was Major General Philip Kearny of American Civil War fame . Kearny Mesa , an area of San Diego , was later named after him . Two U . S . postage stamps relate to Kearny . Scott catalog number 970 , printed in 1948 , commemorates Fort Kearny , and number 944 , issued in 1946 , the capture of Santa Fe . The accuracy of the latter ' s depiction has been questioned .