The Martha series of robots were robots created by the Second Doctor to do housework. He went to the United States of America in 1971 to sell them, and they soon became widespread. The Quarks seized control of the Marthas and turned them against Humans as a prelude to an invasion of America.
The Doctor regained control of the Marthas and had them battle the Quark forces across the nation, leading to the aliens' defeat. (TVC: Martha the Mechanical Housemaid)