After graduating from high school, in response to the start of the Spanish–American War, Davis entered the military service on July 13, 1898, as a temporary first lieutenant in the 8th United States Volunteer Infantry, an all-African-American unit.
This regiment was stationed at Chickamauga Park, Georgia, from October 1898 until the unit was disbanded in March 1899.
During the war, Davis briefly served in Company D, 1st Separate Battalion of the Washington D.C. National Guard.

Davis was mustered out on March 6, 1899, and on June 18, 1899, he enlisted as a private in Troop I, 9th Cavalry Regiment (one of the original Buffalo Soldier regiments), of the Regular Army.
At his post in Fort Duchesne, Utah, he served first as the troop's clerk and later as squadron sergeant major through 1900.
In late 1900, Davis's unit was commanded by Lieutenant Charles Young, the only African-American officer serving in the US military at that time.
Young encouraged Davis's ambition to become an officer.
Young tutored Davis in all of the subjects that were covered in the officer candidate test, especially mathematics, which had been Young's most difficult subject at the United States Military Academy at West Point.
In early 1901 Davis passed the test at Fort Leavenworth, Kansas, his highest score coming in the math section. (
A second African American, John E. Green, passed the test along with 10 other soldiers.)
On February 2, 1901, Davis was commissioned a second lieutenant of Cavalry in the Regular Army.

In the spring of 1901, Troop I was posted overseas to serve in the Philippine–American War.
In August 1901, Davis was assigned to Troop F, 10th Cavalry, where he assumed the duties of a second lieutenant.
Troop F returned to the US in August 1902.
Davis was then stationed at Fort Washakie, Wyoming, where he also served for several months with Troop M. In September 1905, he was assigned to Wilberforce University in Ohio as Professor of Military Science and Tactics, a post that he filled for four years.

In November 1909, shortly after being ordered to Regimental Headquarters, 9th Cavalry, Davis was reassigned for duty to Liberia.
He left the United States for Liberia in April 1910, and served as a military attaché reporting on Liberia's military forces until October 1911.
He returned to the United States in November 1911.
In January 1912, Davis was assigned to Troop I, 9th Cavalry, stationed at Fort D. A. Russell, Wyoming.
In 1913, the 9th Cavalry was assigned to patrol the Mexican-United States border.

In February 1915, Davis was again assigned to Wilberforce University as Professor of Military Science and Tactics.
From 1917 to 1920, Davis was assigned to the 9th Cavalry at Fort Stotsenburg, Philippine Islands, as supply officer, commander of 3rd Squadron, and then of 1st Squadron.
He reached the temporary rank of lieutenant colonel but returned to the United States in March 1920 with the rank of captain.

Davis was assigned to Tuskegee Institute (now Tuskegee University) in Tuskegee, Alabama, as the professor of military science and tactics from 1920 to 1924.
He then served for five years as an instructor with 2nd Battalion, 372nd Regiment, Ohio National Guard, in Cleveland, Ohio.
In September 1929, Davis returned to Wilberforce University as professor of military science and tactics.
He was assigned to the Tuskegee Institute in the early part of 1931 and remained there for six years as a professor of military science and tactics.
During the summer months of 1930 to 1933, Davis escorted pilgrimages of World War I Gold Star mothers and widows to the burial places of their loved ones in Europe.

In August 1937, Davis returned to Wilberforce University as professor of military science and tactics.
Davis was assigned to the 369th Regiment, New York National Guard, during the summer of 1938, and took command of the regiment a short time later.
Davis was promoted to brigadier general on October 25, 1940, becoming the first African-American "brigadier" general in the United States Army.

It should be noted the term "General" is loosely used or infor
After graduating from high school, in response to the start of the Spanish–American War, Davis entered the military service on July 13, 1898, as a temporary first lieutenant in the 8th United States Volunteer Infantry, an all-African-American unit. This regiment was stationed at Chickamauga Park, Georgia, from October 1898 until the unit was disbanded in March 1899. During the war, Davis briefly served in Company D, 1st Separate Battalion of the Washington D.C. National Guard.
Davis was mustered out on March 6, 1899, and on June 18, 1899, he enlisted as a private in Troop I, 9th Cavalry Regiment (one of the original Buffalo Soldier regiments), of the Regular Army. At his post in Fort Duchesne, Utah, he served first as the troop's clerk and later as squadron sergeant major through 1900. In late 1900, Davis's unit was commanded by Lieutenant Charles Young, the only African-American officer serving in the US military at that time. Young encouraged Davis's ambition to become an officer. Young tutored Davis in all of the subjects that were covered in the officer candidate test, especially mathematics, which had been Young's most difficult subject at the United States Military Academy at West Point. In early 1901 Davis passed the test at Fort Leavenworth, Kansas, his highest score coming in the math section. (A second African American, John E. Green, passed the test along with 10 other soldiers.) On February 2, 1901, Davis was commissioned a second lieutenant of Cavalry in the Regular Army.
In the spring of 1901, Troop I was posted overseas to serve in the Philippine–American War. In August 1901, Davis was assigned to Troop F, 10th Cavalry, where he assumed the duties of a second lieutenant. Troop F returned to the US in August 1902. Davis was then stationed at Fort Washakie, Wyoming, where he also served for several months with Troop M. In September 1905, he was assigned to Wilberforce University in Ohio as Professor of Military Science and Tactics, a post that he filled for four years.
In November 1909, shortly after being ordered to Regimental Headquarters, 9th Cavalry, Davis was reassigned for duty to Liberia. He left the United States for Liberia in April 1910, and served as a military attaché reporting on Liberia's military forces until October 1911. He returned to the United States in November 1911. In January 1912, Davis was assigned to Troop I, 9th Cavalry, stationed at Fort D. A. Russell, Wyoming. In 1913, the 9th Cavalry was assigned to patrol the Mexican-United States border.
In February 1915, Davis was again assigned to Wilberforce University as Professor of Military Science and Tactics. From 1917 to 1920, Davis was assigned to the 9th Cavalry at Fort Stotsenburg, Philippine Islands, as supply officer, commander of 3rd Squadron, and then of 1st Squadron. He reached the temporary rank of lieutenant colonel but returned to the United States in March 1920 with the rank of captain.
Davis was assigned to Tuskegee Institute (now Tuskegee University) in Tuskegee, Alabama, as the professor of military science and tactics from 1920 to 1924. He then served for five years as an instructor with 2nd Battalion, 372nd Regiment, Ohio National Guard, in Cleveland, Ohio. In September 1929, Davis returned to Wilberforce University as professor of military science and tactics. He was assigned to the Tuskegee Institute in the early part of 1931 and remained there for six years as a professor of military science and tactics. During the summer months of 1930 to 1933, Davis escorted pilgrimages of World War I Gold Star mothers and widows to the burial places of their loved ones in Europe.
In August 1937, Davis returned to Wilberforce University as professor of military science and tactics. Davis was assigned to the 369th Regiment, New York National Guard, during the summer of 1938, and took command of the regiment a short time later. Davis was promoted to brigadier general on October 25, 1940, becoming the first African-American "brigadier" general in the United States Army. 
It should be noted the term "General" is loosely used or infor
Benjamin O. Davis Sr.