Mr. Arthur Donwell Coates Sr. of Aberdeen, MD passed into eternal rest on January 22, 2026 at the age of 97 at home surrounded by his loving family. He was the only child of the late Arthur Raymond and Margaret June Coates of Colliers, West Virginia. He was pre-deceased by his wife, Marie Silver Coates to whom he was married for more than 60 years. He is survived by sons Arthur D. Coates Jr. (Lindsay) of Bel Air, Randolph S. Coates (Laurel) of Havre de Grace, and Stephen T. Coates of Aberdeen who was his dedicated caregiver in the final years of his life. He is also survived by 7 grandchildren and 8 great-grandchildren including, Caroline P. C. Huether (Timothy) and son John R. Huether, Andrew S. Coates (Katherine) and sons Alden S. and Harrison O. Coates, Rebecca A. Coates, Katherine E. Gilinsky (Jacob), Kristin M. Carr (Jesse) and sons Jesse A. and Drew S. Carr, Matthew D. Coates (Erin) and children Anne F. and Daniel P. Coates, and Taylor M. Coates (Jacquelyn) and son Callahan Q. Coates, and several nieces and nephews including George "Wesley" Bobberts (Tina) who Arthur and his wife Marie helped raise. He is also survived by many Thompson family relatives from his original West Virginia home and other states, including his cousin Peggy J. Chatfield (Dale) who showered him with love and thoughtfulness during his final years.

Arthur spent his early years in Colliers, a very small, tight-knit town in the West Virginia panhandle where he was affectionately known to everyone as "Boots". He was only one generation removed from immigrants, his grandparents, who came to the US from Ireland and Scotland. It was here, in the midst of coal mines and steel mills, that he learned the work ethic, the trade skills, and the sense of community that built the foundation of his life. Life could be harsh here and there were no hand-outs, so when he wasn't enjoying the freedom of growing up in the West Virginia countryside, he was working and learning. At an early age he sold seeds door-to-door, picked apples and other crops on a local farm, and learned trade skills and automobile repair. In high school he worked in a near-by rail yard repairing box cars and track. 

A defining moment for Arthur came during elementary school when he was amazed to learn that banks would pay interest on deposits and in short order his parents helped him open his first account. This was the start of a life-long passion for knowledge of the world of finance and investing. For most of his adult life, Arthur read the Wall Street Journal daily and in all of his activities, he strived to show others the opportunities that existed to get ahead through investments and wise financial decisions.

He graduated from Follansbee High School, West Virginia and in 1950 he was awarded his Bachelor Degree in Chemistry from the College of Steubenville (now the Franciscan University of Steubenville), the first person in his family to earn a college degree. Later, he received his Master's Degree in Chemistry from the University of Delaware.

After receiving his Bachelor Degree, he was employed briefly at the Wheeling Steel Corporation and from there he served in the US Army from 1951-1953. The Army assigned him to serve in a special science and technology unit at the Aberdeen Proving Grounds, MD. It was during this time that he met his future wife, Marie Maslin Silver, from Havre de Grace. After Army service, he stayed at Aberdeen Proving Ground and was employed as a Research Chemist at the US Army Ballistic Research Laboratory until he retired in 1986 from the position of Special Assistant to the Director, with 35 years of service to the US Army. At BRL, Arthur published technical papers and was awarded patents in the field of combustion science and terminal ballistics. He attended the Oak Ridge Institute of Nuclear Science and the Oak Ridge School of Nuclear Reactor Technology and participated in related research topics. He was a member of national committees, a fellow of the American Institute of Chemists, and was a member of the American Chemical Society for 75 years. He was recognized by American Men of Science and Engineering and Who's Who in the East.

Arthur was the first male in his family to retire.  Growing up, he saw family and friends work until the day they died, some in industrial accidents and others, like his father, from health issues. His grandfather died in his 70s, walking home after working his shift in a local coal mine. But Arthur valued the opportunities of time, life, and giving too much to relax. Instead, he took on new challenges to support his family and his community. Throughout his life, Arthur served his local community unselfishly including serving as a Board member and past President of the APG Federal Credit Union, as a leader in the National Association of Investors Corporation to help others learn how to invest wisely, as Financial Officer for the Susquehanna Lockhouse Museum in Havre de Grace, as a Board Member of the Harford Historical Society and a Board Member of the Chamber of Commerce of Aberdeen MD. Arthur also served as an officer in the Lions Club of Aberdeen MD, was President of the Friends of the Aberdeen Public Library and volunteered his time to help local citizens prepare their tax returns. He also served for many years as an Officer, and then President, of Silver Farms, Inc, a business created by his wife's parents, Frank and Marie Silver. He provided a sure and steady hand to guide Silver Farms through many complex matters.  Arthur was also a long-standing member of the Grace United Methodist Church, Aberdeen MD where he served in many roles including Lay Leader and was also past-President of the Church's Baker Cemetery. In addition, Arthur was a Mason; a member of the Mt. Ararat #44 Lodge, in Bel Air MD for more than 50 years and was also a member of the Scottish Rite and Boumi Shrine of Baltimore MD.

When his beloved wife Marie took ill later in life, Art took her care into his hands and nursed her through many challenges, with the help of his son Stephen. This was the hallmark of his life, no matter what, Arthur Coates always stepped up. He never shied away from the challenges that life threw at him especially when it came to supporting and protecting his family.

Arthur was an amazing person who was as comfortable with the complexities of chemistry, research and development for the Army, intricacies of investments and Wall Street, the law, real estate, and history as he was working with his hands to fix a car, build his own 5-car garage, or even to dig a ditch. No job was beneath him and no challenge was too hard. Beyond all of his other accomplishments, Arthur's greatest legacy is the endless love, guidance and support he gave to his immediate and extended family. No matter what was needed, in partnership with his beloved wife Marie, he always found a way to provide. His generosity was unbounded. In his later years, the gradual loss of capabilities frustrated him because he couldn't do what he wanted to. When asked how he was doing he would sometimes say, "I'm not making much progress". But no matter how hard things became, he never complained. He persevered with courage and dignity until he was called home. 

We offer on his behalf the blessing that he gave in his last years whenever we parted: "May God bless, guide, and protect you, all the days of your life".

Funeral services are arranged through the Zellman Funeral Home, Havre de Grace MD. Celebration of life will be held on February 3rd from 2-4 PM and from 6-8 PM. Funeral service will be held at the Grace United Methodist Church, Aberdeen MD on February 4th at 1100 AM with interment to follow at the Baker Cemetery, Aberdeen MD. Pallbearers are Andrew S. Coates, Timothy J. Huether, Jacob F. Gilinsky, Matthew D. Coates, Taylor M. Coates, and Jesse R. Carr. Honorary Pallbearers are Caroline P.C. Huether, Rebecca A. Coates, Katherine E. Gilinsky, Katherine E. Coates, Kristin M. Carr, Erin F. Coates, and Jaclyn R. Coates.

In lieu of flowers, the family suggests making a donation in honor of Arthur to either the Fisher House Foundation, Inc, for the benefit of active-duty and veteran service members and their families (https://www.fisherhouse.org), the Colliers United Methodist Church, 318 Pennsylvania Ave. P.O. Box 184, Colliers, WV 26035, or the Grace United Methodist Church, 110 West Bel Air Avenue, Aberdeen, MD 21001.