Montowampate was the second son of Nanapashemet and Squaw Sachem. Several years after his father's death, Squaw Sachem would install Montowampate as sachem of Saugus. Saugus back then was roughly all the land between present-day Boston and Salem, Massachusetts.
The English said Montowampate never caused them trouble, but they believed his disposition to be worse than that of his brother Wonohaquaham. All that likely meant is that Montowampate rejected the idea of religious conversion. The English gave Montowampate the name Sagamore James.
The first settlers of Lynn, Massachusetts testified that it was Montowampate that allowed them to settle on his territory in Saugus around 1629. Montowampate would have been about 20 years old at that time.
In that same year Montowampate would marry Wanunchus. She was the daughter of Passaconaway, the Great Bashaba of the Pennacook along the Merrimack River in New Hampshire.
In 1631 Montowampate and his brother Wonohaquaham were wounded at Agawam in a battle with their old enemy from the north. Montowampate's wife Wanunchus was kidnaped in the siege and taken prisoner. A ransom was paid and she returned home two months later.
Montowampate died during the terrible plague of 1633. He did have children and two granddaughters who lived in Pennacook territory, but not much is known about them.