On this date in 1637, Connecticut colonists formally declared war against the Pequots, the Native American tribe whose territory covered approximately 250 square miles of land in southeastern Connecticut and Rhode Island.
Relations between Connecticut colonists and the Pequots had been tense ever since the first permanent English settlements had been established along the Connecticut River valley only a few years before. Both the Pequots and English believed the other to be encroaching on cherished trade routes. In 1636 — when most English colonial settlements weren’t even two years old — a series of tense standoffs and retaliatory raids culminated in a seven-month siege of the small, palisaded English fort at Old Saybrook by the Pequots. The siege finally ended in early 1637 when Massachusetts sent a regiment of troops to reinforce the Connecticans at Saybrook; the Pequots disbanded, but continued to harass English settlers elsewhere in the region.
Despite the increasingly rapid deterioration of English-Indian relations, the English, wary of being outnumbered by their Native neighbors, were still reluctant to declare outright war against the Pequots. The tipping point came in late April 1637, when a large band of Pequot and Wangunk warriors raided the town of Wethersfield, Connecticut. Nine men and women were killed, and two girls (later rescued by Dutch traders) were captured and taken into Pequot territory.

The deadly Wethersfield attack convinced colonial leaders who had been wary of formally engaging the Pequots that a declaration of war was necessary in order to ensure the survival of English settlers in Connecticut. Just three weeks after colonial leaders declared war, a combined force of nearly 70 Englishmen and 300 native allies launched a surprise attack on a fortified Pequot village near present-day Mystic, Connecticut, killing anywhere from 400 to 700 Pequots. The event, alternately known as the Battle of Mistick Fort or the Mistick Fort Massacre, became the most infamous example of the brutality that characterized the Pequot War. The war continued for sixteen bloody months and, as the tide turned in favor of the English settlers and their Indian allies, resulted in a permanent shift in the balance of power in the territory surrounding Connecticut. On September 21, 1638, representatives from the Pequot and Mohegan tribes met with English colonists to sign the Treaty of Hartford, which marked the end of the Pequot tribe’s longstanding era of dominance over the peoples of southern New England and put an end to the war that first began on this day in Connecticut history.
Further Reading
“The History of the Pequot War,” Battlefields of the Pequot War Project
Kevin McBride and Laurie Pasteryak Lamarre, “Exploring and Uncovering the Pequot War,” Connecticut Explored
Walter Woodward, “Two Controversial Statues Standing… At Least, For Now,” Connecticut Explored