After the Halifax Explosion in Nova Scotia in 1917 , a medical detachment from the Massachusetts State Guard was among the first units to arrive and offer aid . As an expression of gratitude for the aid provided by the Boston Red Cross and the Massachusetts State Guard , the city of Halifax sent the city of Boston a Christmas tree , a gift which was revived in the form of an annual tradition conducted by the province of Nova Scotia in 1971 which continues to this day . During the 1918 flu pandemic , the Massachusetts State Guard operated nine hospitals to treat civilians
Halifax Explosion
Halifax Explosion
Massachusetts State Defense Force