An Aquinnah Wampanoag elder and lifelong advocate for Indigenous rights, Wamsutta is best known for the rescinded invitation he received to the 350th celebration of the Plymouth pilgrims landing at Plymouth Rock in 1970. After seeing the speech he intended to deliver, Wamsutta was uninvited to the colonial celebration. Wamsutta and other activists went anyways and disrupted the colonial celebration, declaring Thanksgiving a National Day of Mourning for Native Americans- a tradition which continues today in Massachusetts. Wamsutta was also involved in the Trail of Broken Treaties takeover the Burea of Indian Affairs building in 1972, and the Longest Walk from California to Washington, DC in 1978. Wamsutta helped found United American Indians of New England, which organizes the National Day of Mourning and was their moderator from the 1970's to the mid 1990's.