The history of the National Guard began on December 13, 1636, when the General Court of the Massachusetts Bay Colony ordered the organization of the Colony's militia companies into three regiments: The North, South and East Regiments. The colonists had adopted the English militia system which obligated all males, between the ages of 16 and 60, to possess arms and participate in the defense of the community. The early colonial militia drilled once a week and provided guard details each evening to sound the alarm in case of attack. The growing threat of the Pequot Indians to the Massachusetts Bay Colony required that the militia be in a high state of readiness. The organization of the North, South and East Regiments increased the efficiency and responsiveness of the militia. Although the exact date is not known, the first muster of the East Regiment took place in Salem, Massachusetts. The National Guard continues its historic mission of providing units for the first-line defense of the nation. The 101st Engineer Battalion, Massachusetts Army National Guard, continues the East Regiment's proud heritage of 350 years of service.