Born in Wurtemberg, Germany, September 21st, 1847.  Came to the United States in the early winter of 1852 and settled in Jerome Township, Union County, Ohio.  Attended the common schools of Jerome Township, and from September, 1863, to June, 1866, the Central High School of Columbus, Ohio, from which he was graduated in June, 1866.
     He then entered the law office of Mr. James W. Robinson in Marysville, Ohio, as a student, in the summer of 1867.  Entered the United States Military Academy at West Point, New York,,, under an appointment received through Hon. John Beatty, M. C., in June,  1868, and was graduated at the institution number 16 in a class of 56 members, June, 14th 1872.
     He was appointed Second Lieutenant in the 17th U. S. Infantry and joined his company, which was then stationed at the Cheyenne River Indian Agency, on the Missouri River in South Dakota.  Served at that post on the Indian frontier among the Sioux and Minnecoujoix Indians until the spring of 1877, when he was detached from his command and sent with an expedition to the junction of the Big Horn and Little Big Horn Rivers in Montana, where he served as quartermaster in charge of the construction of the military post, Fort Custer, remaining on that duty until June, 1878, when he was transferred to the Black Hill country in South Dakota and as quartermaster had charge of the construction of the military post, Fort Meade, near Deadwood, South Dakota, until the spring of 1879, when he again joined his company at Fort Sisseton, Minnesota, and remained with it until June, 1881, when he was appointed Professor of Military Science and Tactics at the Ohio State University at Columbus, Ohio, at which place he served until July, 1884.
     Returned to duty with his company, then stationed at Fort Totten, North Dakota, in September, 1884, and went with the company to Fort D. A. Russell, near Cheyenne, Wyoming.  Appointed Adjutant of the 17th Infantry in September, 1889, and transferred to the Quartermaster's Department as Captain and Assistant Quartermaster, in August, 1890.  As Quartermaster he took part in the Pine Ridge Indian uprising and campaign from December, 1890, to February, 1891.  Was transferred in the spring of 1891 to El Paso, Texas, to take charge of construction of the new post, Fort Bliss.  Transferred to Detroit, Mich., for construction work at Fort Wayne, thence to Fort Riley, Kansas, and from there, in the winter of 1897-98, to Southeastern Alaska, as Quartermaster of the Alaska Relief Expedition.
     At the outbreak of the Spanish war, in the spring of 1898, Captain Ruehlen was at Dyea, Alaska, and in May, 1898, was sent to San Francisco, Cal., where he was assigned to duty in connection with the preparation of transports carrying to duty in connection with the preparation of transports carrying troops and supplies to the Philippine Islands.  Was transferred to Honolulu, Hawaii, in August, 1898, as Depot Quartermaster and in charge of the transport service there, where he remained until September, 1900, when he was sent to Seattle, Washington, for duty as Depot Quartermaster there.
     On duty in the office of the Quartermaster General in Washington, D. C., in charge of the Department of Construction and Repair, from March, 1902, to May, 1908.  Depot Quartermaster at Jeffersonville, Ind., May, 1908, to May, 1909.  In the Quartermaster General's office, Washington, D. C., from May, 1909, to June, 1911.
     Retired from active service, having reached the limit of age established by law, in September, 1911.
     His successive promotions to the Regular Army were:  Second Lieutenant, 17th Infantry, June 14th, 1872; First Lieutenant, 17th Infantry, September, 1876; Captain-Assistant Quartermaster, August, 1890; Major and Quartermaster, January, 1900; Lieutenant Colonel, August, 1903; Colonel and Assistant Quartermaster General, February, 1908.