John David McMahon III passed away Wednesday, April 15, 2015, following a brief illness. He was born in Cambridge, MA on January 5th, 1953, and was a New Hampshire resident for most of his adult life. John proudly served his country in the United States Air Forces from 1975-1977. He is survived by his mother, Mary L. McMahon, his brother, James R. McMahon, his sisters, Jennifer R. (McMahon) LaFrance and Janine M. (McMahon) Goodwin, and a number of nieces and nephews. John was predeceased by his father, John David McMahon II, and his sister, Janice (McMahon) Noonan-Miles. Funeral services will be private. Donations in lieu of flowers to be made to the New England Center for Homeless Veterans, 17 Court Street, Boston, MA, 02108.