 It is the nation's second-oldest active military base.At the intersection of Indian trails along Letort Creek, in the eighteenth century the town of Carlisle became the jumping-off point for traders and settlers heading over the Alleghenies on their way west.A brief 1756 encampment at Carlisle preceded the more permanent settlement in May 1757 during the French and Indian War between the colonies of Britain and France, when Colonel John Stanwix marched upstream with British regulars and provincials against the backdrop of the international Seven Years' War.