The city where the 10th Regiment Massachusetts Volunteer Infantry was organized is in what Massachusetts county?
10th Regiment Massachusetts Volunteer Infantry:  Organized at Hampden Park in Springfield, Massachusetts in the early summer of 1861 and consisting mostly of men from western Massachusetts, the regiment was mustered in on June 21, 1861. Springfield, Massachusetts: Springfield is a city in western New England, and the seat of Hampden County, Massachusetts, United States.
Hampden County