Miantonomi and Canonicus lived and ruled in a period of extreme change for the Narragansett. Although there were no colonists in the region when Miantonomi was born (c. 1600), early trading interactions between Europeans and First Peoples eventually turned into increasing waves of colonists arriving. By 1640, there were 20,000 English in southern New England. Miantonomi and Canonicus ruled as dual Sachems. A Sachem is a paramount leader or chief in an Algonquian tribe. The practice of having dual Sachems was common among the Narragansett and other Algonquians.
In 1636, Canonicus and his nephew Miantonomi befriended Roger Williams, a newcomer to the area who had been banished by the Massachusetts Bay Colony. The uncle and nephew deeded Williams a portion of land in 1638, which Williams named Providence. One of the boundary markers was Neutaconkanut Hill, a visible high point.
While to Williams this transaction meant that he owned these lands, to the Narragansett, land could never be bought or sold. As such, they likely thought that they were sharing land with Williams and his followers. Subsequently, the Narragansett were shocked when they were unable to move freely about the land, with fences and stone walls at every turn and courts readily prosecuting them for trespassing--a very foreign concept indeed.
At the time, colonists knew of Miantonomi's political power in the region. In 1632, Boston even hosted him for a formal dinner. Governor Winthrop remarked that Miantonomi "was very deliberate and showed good understanding of justice, equity, and ingenuity."
During the Pequot War (1636-37), the Narragansett, led by Canonicus and Miantonomi, allied with the English against the Pequots, who were enemies prior to European arrival. Williams' colony was essentially left defenseless if not for the Narragansett's support of the English. At the time, Narragansett animosity also extended to the Mohegan Tribe. The Mohegan Tribe were a group of Pequots that previously separated and had become increasingly hostile because of English encroachment and disagreements between two Sachems: Sassacus and Uncas. Although enemies with the Pequots, the Narragansett were horrified when the English killed Pequot women and children at Mystic Fort during the war. This went against the Narragansett code of war and was an act the English had sworn they would not do. From then on, Miantonomi increasingly distrusted the English.
After the war, rumors soon swirled that Miantonomi was planning an uprising. In the fall of 1640, Miantonomi was again called to Boston, but this time it was to answer conspiracy charges. Miantonomi asked Roger Williams to serve as his interpreter, but Williams, having only been banished five years earlier, did not accompany him. Shortly after the meeting, the newly formed United Colonies of New England learned of a rousing speech Miantonomi made to encourage tribes to join him in an uprising. The United Colonies wanted Miantonomi to be stopped.
In 1643, Uncas, the Mohegan Sachem, finally captured Miantonomi and brought him to Hartford, where the English held him as a prisoner. Not knowing what to do with him, they returned Miantonomi to the Mohegan, which was likely a strategy to pit Native communities against each other. In captivity, Miantonomi was assassinated by Wawequa, Uncas' brother, which likely relieved the United Colonies. Canonicus died in 1647, reportedly brokenhearted from the loss of his nephew.