Bendell entered the service in the 39th New York Volunteer Infantry Regiment as a hospital steward in 1861 and was later appointed assistant surgeon.

[6] In furthering President Grant's "Peace Policy" and choosing agents beyond the Quaker faith, with the urging of the Jewish community leader Simon Wolf, Bendell was appointed superintendent of Indian Affairs for the Arizona Territory.

His first task was to accompany Gen. Oliver Otis Howard and members of various Indian tribes and the first Apache delegation to Washington, DC.

[11] Dr. Bendell accompanied five of the Native American chiefs on a brief excursion to his home in Albany, stopping at the temperance hotel founded by Edward C. Delavan.

Dr. Bendell's report to Washington Indian Affairs commissioner Francis Amasa Walker, reprinted in New York Times,[14] notes the tribal reluctance to accept the reservation conditions offered by the Government and the Native American hoarding of rations for the purpose of renewing raids upon settlers.

Dr. Bendell was the superior officer of agent Tom Jeffords, chosen by Apache chief Cochise after a treaty made with General Oliver Otis Howard.

[18] After his posting in Denmark, Dr. Bendell spent a year studying ophthalmology under the noted professor Otto Heinrich Enoch Becker in Heidelberg, Germany.