Harold Bruce Mueller, known to all as Bruce and a longtime Concord resident, passed away after a period of declining health on Wednesday January 19, 2022 at age 83. The grandson of German immigrants, he was born July 18, 1938 in Missoula, Montana to Theodore and Helen (Hubbard) Mueller. Bruce attended Saint Anthony's parochial school and Missoula County High School and spent his free time working at the town's drug store. By age 14, he was running the evening shift at Hollyoke Drug by himself. Into his 80s he could still recite its soda counter menu from memory. At 17, Bruce attended the University of Montana, where he joined the Army ROTC, learned German, and majored in physics. After graduation he served in Germany. In 1962 he began graduate school for applied mathematics at New Mexico State in Las Cruces, where he met his future wife, Mary Sandra Marks. He trained at the U.S. Army's Ordnance Guided Missile School at Redstone Arsenal in Huntsville, Alabama, and served his country in the Vietnam War. Upon returning to the U.S., he was stationed at White Sands Missile Range, where he and Sandra were married in 1969. He served in Korea, and at various Army posts, including Picatinny Arsenal in New Jersey. Bruce retired from the Army in 1979 as a Lieutenant Colonel. He moved his family to Concord and worked at Raytheon until his retirement in 1995, after which he started KMS Associates, a consulting firm. Bruce was a longtime communicant and lector at Holy Family Parish and was known for his distinct bass voice that some said sounded "just like the voice of God talking to you." He volunteered with Concord Boy Scout troop 132, and was a member of the Concord Independent Battery, helping to fire the cannon on Patriot's Day, Memorial Day, and Veteran's Day. He loved Dobermans, baked excellent Irish soda bread, always salted cantaloupe, and made a mean eggs benedict with homemade hollandaise. He had a penchant for precision and collected antique pendulum clocks that he kept in running condition. Bruce is survived by his wife of 52 years, Mary Sandra Mueller; a sister Marcia Jacky of Libby, Montana; three sons, Kurt (Lucrecia) Mueller of Issaquah, Washington, Mark (Mary) Mueller of Russell, MA, and Seth (Johanna) Mueller of Skellefteå, Sweden; four grandchildren; and several nieces and nephews. He was predeceased by his brother, Theodore Mueller. Family and friends will gather for visiting hours in the Dee Funeral Home, 27 Bedford Street, Concord Center on Monday, January 24th from 5 to 7 pm. Bruce's Funeral Mass will be celebrated on Tuesday, January 25th at 10 am in Holy Family Parish, Monument Square, Concord Center. Burial with U.S. Army military honors will follow at St. Bernard's Cemetery in Concord. Concord's Town Flag will fly at half-staff on Tuesday, January 25th in recognition of Bruce's faithful and honorable military service to our country. In lieu of flowers, the family suggests donating in his memory to the Society of St. Vincent de Paul, c/o Holy Family Parish, P.O. Box 220, Concord, MA 01742. Arrangements are under the care of Dee Funeral Home & Cremation Service of Concord.