Mexican-American War Shortly after graduation he was promoted to 2nd Lieutenant in the 1st U.S. Dragoons and participated in the
Mexican–American War, and was engaged in considerable military action at the
Battle of San Pasqual and the
Battle of Rio San Gabriel. On May 15, 1850, Davidson and Captain
Nathaniel Lyon led a regiment of the 1st U.S. Dragoons in a massacre of the Pomo population of the island of Bo-No-Po-Ti in northern California.
Western Indian Wars Following the Mexican-American War, Davidson was promoted to 1st Lieutenant and assigned to the
Western frontier, where he served as the regimental quartermaster and adjutant. He led two companies of the
1st Dragoon Regiment against the
Jicarilla Apaches in the
Battle of Cieneguilla on March 30, 1854, where he was badly defeated in the fourth-worst defeat suffered by the American military during the Western Indian Wars. In 1855 Davidson, who had still earned praise for commanding at Cieneguilla, was promoted captain and was in command of
Fort Tejon, California when the American Civil War erupted. In 1851, he married Clara McGunnegle, the daughter of a merchant in
St. Louis, and they had several children.
American Civil War He was allegedly offered a commission in the
Confederate Army, but turned it down. Davidson was transferred to the east and took command of a brigade in the newly formed
Army of the Potomac. On February 6, 1862, President
Abraham Lincoln appointed Davidson to the grade of brigadier general of U.S. volunteers, to rank from February 3, 1862, the same day the U.S. Senate confirmed the previously submitted nomination. General Davidson assumed command of the 3rd Brigade, 2nd Division,
IV Corps during the
Peninsula Campaign. He fought at the battles of
Yorktown and
Williamsburg. During the
Seven Days Battles he received brevet promotions in the
Regular Army for his service at
Gaines' Mill and
Golding's Farm. Shortly after the culmination of the Seven Days' fighting, Davidson was transferred to the
Trans-Mississippi Theater where he was placed in command of the Dist. of St. Louis. From December 3, 1862, to March 26, 1863, he was also in command of the so-called
Army of Southeast Missouri until much of his army was transferred to Ulysses S. Grant in preparation for the
Vicksburg Campaign. He retained command of the Dist. of St. Louis until June 16, 1863, when he briefly commanded the Dist. of Southeast Missouri. From August 10 to November 3, 1863, Davidson commanded the 1st Division of
Frederick Steele's
Army of Arkansas in his most distinguished role in the west. He led Union advance into central Arkansas and won the
Battle of Bayou Fourche, which led directly to the fall of Confederate-held
Little Rock. After the Little Rock expedition, Davidson commanded the cavalry in the Dept. of the Gulf before returning to command the cavalry in the Dist. of Southeast Missouri.
Davidson's raid Beginning November 27, 1864, Davidson was ordered to lead a 4,000 strong cavalry raid from the
Union Army held
Baton Rouge, to sever the M & O Railroad near
State Line, Mississippi. The raid was intended to divert resources away from Confederate John Bell Hood's operations near
Nashville, and to threaten and harass
Mobile. Additionally, the raid was to support Sherman's March to the Sea by requiring the Confederates to keep resources in the Mobile theater of operations. After departing Baton Rouge Davidson's forces reached Greensburg capturing several Confederate prisoners, on November 29, 1864, then to Tangipahoa where they captured a confederate conscript camp and destroyed the New Orleans, Jackson Great Northern Railroad. On December 3, 1864, Davidson's Raiders crossed the
Pearl River and entered
Marion County, Mississippi, occupying Columbia the next day. While in Columbia the cavalry foraged extensively in the area. General Davidson then ordered a diversionary feint toward's Monticello, Mississippi led by Major Seth Remington. After engaging in a brief skirmish outside Columbia Davidson's forces headed east towards Augusta. Upon Davidson's arrival receipt of certain intelligence made him alter his plans. An excerpt from Davidson's official report provides: "The day after my arrival at Augusta I found Mobile papers containing full accounts of our strength and design and our daily progress and marches were telegraphed to Meridian Where Gen. R. Taylor had his headquarters, and to Mobile." As a result, Davidson decided to divide his command, sending a small element of the 2nd New York Veteran Cavalry, 1st Louisiana Cavalry, and a detachment of the 11th New York Cavalry under the command of Lt. Col. Asa Gurney north via Leakesville to destroy telegraph lines and a bridge on the Mobile and Ohio at State Line near the Alabama line, while he continued on toward Farley's Ferry. On December 10, 1864, elements of Davidson's forces met two regiments of Confederate Cavalry near
Leakesville, Mississippi at McLeod's Mill. During the ensuring Battle of McLeod's Mill, one Union soldier stated the lead flew faster than he had ever seen before. The Confederates kept falling back to their main body. Finally, Lieutenant Albert Westinghouse, in command of the first squadron, was ordered to draw sabre and make a charge, which took them past the mill. Westinghouse in the vanguard spurred his horse and shouted to his men to "follow me", all the while swinging his sabre overhead. Westinghouse was shot in the stomach while making the charge and died shortly thereafter. Three charges were made against the Confederates after they had fallen back on their main body. The Union detachment soon realized they were now facing superior numbers with the advantage interior lines of communication, and therefore abandoned the mission. After withdrawing from the engagement, the Confederates did not follow in pursuit. When the fight concluded, three soldiers from the 2nd New York were killed, including Company B's 1st Lt. Albert Westinghouse along with Sgt. Theodore Moss and James Woods of Company A. After this struggle, two days later, Gurney rejoined Davidson's main column. According to different accounts around fourteen or fifteen Confederates were killed along with several being taken prisoner by the withdrawing column. On April 10, 1866, President Johnson nominated Davidson for appointment to the grade of brevet brigadier general, U.S. Army, to rank from March 13, 1865, and the U.S. Senate confirmed that appointment on May 4, 1866. On July 17, 1866, President Johnson nominated Davidson for appointment to the grade of brevet major general, U.S. Army, to rank from March 13, 1865, and the U.S. Senate confirmed the appointment on July 23, 1866. ==Post-war service==