All data about this family was extracted from the 1850 census of West Earl township of Lancaster County, PA.
While it is unclear if the following information pertains to this John B. Mumma, it is highly likely
Civil War Conscientious Objectors -- by county (Lancaster-York) and township.
http://www.libertynet.org/gspa/CivilWarCO1B.htm
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Provided here is a database of names of Pennsylvania men who refused military service during the American Civil War for reasons of conscience--primarily religious convictions. Volunteers of the Genealogical Society of Pennsylvania transcribed these entries from the "Register of Aliens & Persons Having Conscientious Scruples Against Bearing Arms, 1862," (entry #3168); Records of State and District Offices, 1861-72, Pennsylvania (Part IV), Western Division; Records of the Provost Marshal General's Bureau, Record Group 110; National Archives Building, Washington, DC.
This register serves as an index to original requests for exemption on file as "Conscientious Objector Depositions, 1862" (Series #19.15); Records of the Adjutant General; Records of the Department of Military and Veterans' Affairs, Record Group 19; Pennsylvania State Archives, Harrisburg, PA. In some instances, the depositions show the age and the occupation of the objector, and each one is signed by the man seeking exemption. These papers are arranged first by county and then roughly in alphabetical order by the individual's surname, similar to the entries in the Register. Copies of the depositions may be obtained for a fee from: Reference Section, Pennsylvania State Archives, 350 North Street, Harrisburg, PA 17120-0090
Deposition No Forename MI Surname County Township
3347 John B. Mumma Lancaster West Earl