William Allen and Joseph Turner began iron works at Andover in 1760 on land purchased from a large tract belonging to William Penn. Slaves and indentured servants extracted and processed iron ore there to produce fine grade iron, and the iron mined at Andover was esteemed as excellent for making steel. On January 15, 1778, the mines, forges, and furnaces at Andover were confiscated by an Act of the Continental Congress because their owners were loyal to the British Crown. George Washington's encampment at Morristown, New Jersey, was in part intended to protect these works from falling into British control. The Iron Master's House, occupied by John Hackett, manager for Allen and Turner, stands above the ravine where the iron works was located.