A native of Marion, Virginia, Rosenbaum graduated from the United States Military Academy (West Point) in 1894 and began a career in the Infantry.

As his career progressed, Rosenbaum served with Infantry regiments throughout the United States, frequently in quartermaster, commissary officer, and adjutant posts.

He received temporary promotion to brigadier general, and his wartime service included the Battle of Saint-Mihiel, Meuse–Argonne offensive, Lorraine campaign, and Occupation of the Rhineland.

[1][2] He was raised and educated in Marion, and in 1890 received appointment to the United States Military Academy at West Point from U.S. Representative John A.

[5] Among Rosenbaum's classmates who also attained general officer rank were Clarence C. Williams, Dwight Edward Aultman, Paul Bernard Malone, Hamilton S. Hawkins III, Frank Sherwood Cocheu, Ora Elmer Hunt, Frank Parker, George Henson Estes, Oliver Edwards, Briant H. Wells, and John William Barker.

[6] After returning to the United States in October 1898, he served with his regiment at Fort Wayne, Michigan, where he continued to hold the quartermaster's post.

[7] When the regiment returned to the United States in July 1903, it was posted to Fort Sam Houston, Texas, where Rosenbaum continued to serve as quartermaster until December 1905.

[8] In June 1918, he received promotion to permanent lieutenant colonel and temporary brigadier general, and in July he assumed command of the 158th Infantry Brigade.

[8] After arriving in France, Rosenbaum was reassigned again in September, this time to command of the 155th Infantry Brigade, a subordinate unit of the 78th Division.

[8] He remained in command after the brigade returned to the United States, and led it until demobilization at Fort Gordon, Georgia in August 1919.

[8] After demobilization, Rosenbaum was reduced to his permanent rank of lieutenant colonel and was assigned as deputy commandant of the United States Disciplinary Barracks at Fort Leavenworth, Kansas.

[6] After serving as an instructor for Organized Reserve Corps officers at Fort Devens, Massachusetts in the summer of 1923, in August he was assigned as a student at the United States Army War College, and he graduated in June 1924.

[10] In November and December 1927 he attended the refresher course for officers at the Langley Field, Virginia Air Corps Tactical School.

[6] In November 1929, Rosenbaum was also assigned to command the 78th Division, an Organized Reserve Corps unit based in Newark, New Jersey.