Peter Jethro was born in approximately 1614 and was the son of the Nipmucmedicine manTantamous, although some early records confuse the father and son. Peter Jethro stated that he was "one of the ancient native hereditary Indian proprietors of" Assabet. By 1635 Peter Jethro resided in Nashobah near Concord and was present with a group of Native Americans to witness the sale of what is now downtown Concord to local colonists. Peter Jethro eventually moved to the praying town of Natick near where his father resided on Nobscot Hill, and there he studied under John Eliot by 1650. Eliot's group later vouched for him as a "grave and pious Indian" and commissioned him to work as a missionary minister in Nashaway and Weshakim in 1674. Using his knowledge of English and local Algonquin dialects, Peter Jethro served as a translator and scribe for various land transactions between settlers and Native Americans in Massachusetts. In 1665 he was part of a group of Indians that transferred Quinsigamoge Pond to the settlers.
In 1675 Peter's father, Tantamous, and ten other Indians were falsely accused of committing a murder in the Lancaster raid after allegedly falling under suspicion due to their "singing, dancing, and having much powder and many bullets and slugs hid in their baskets," but they were acquitted when the true murderer, Monoco, a Nashaway, was discovered, and Peter Jethro communicated with the captors of Mary Rowlandson to obtain her release. King Philip captured Peter Jethro at the outbreak of King Philip's War, but Peter escaped and turned himself in to the English authorities in response to an offer of a pardon for any Indian who did so. Peter Jethro accompanied the Indians against the English during their expedition on the Connecticut River and was present at Battle on Beer's Plain in Northfield in 1675, and he freed an English captive. During King Philip's War, the government ordered Peter's father, Tantamous, and his family to Deer Island, but Tantamous escaped, and Peter alerted the authorities of his father's whereabouts, and his father was captured at Cochecho In his history of the war, Increase Mather referred to the incident, stating, "That abominable Indian Peter Jethro betrayed his own Father, and other Indians of his special acquaintance, unto Death." More recent historians suggest that Peter may have actually been working to turn in only John Monoco, the perpetrator of the Lancaster raid, out of a sense of justice, and Monoco and Old Jethro may have intended to surrender peacefully in return for offering Canonicus, the Narragansett leader, in exchange for their lives.
Later life
In 1683 Peter Jethro was living with Jonathan Ting of Dunstable, Massachusetts, and transferred land north of Mount Wachusett to Ting, which Jethro had received from his Uncle Jeffrey of Waymessitt, and Jethro stated that he had no children. In 1684 Peter Jethro confirmed land transfers of family land in Sudbury to colonists, and he deeded land in what is now Maynard to settlers there, and he also signed documentation in 1684 confirming early land transfers including the Concord purchase. Jethro was involved in land transfers in as far away as what is now Vermont. According to one source, "n the Fall of 1688, Peter Jethro and three other Indians went on an excursion to the upper valley of the Connecticut River, the object of which is not stated. No later notice of him has been found."
