The New England Confederation came together in 1643 to discourage attacks from other colonies such as the Dutch in nearby New Netherlands, and American Indians. Named the United Colonies of New England, it was formed by New Haven, Massachusetts, Connecticut, and Plymouth. Rhode Island and other New England colonies were excluded on religious and political grounds. After Massachusetts refused to join in fighting a war against the Dutch, the confederation foundered, finally coming to an end in 1684.
Mercator projection: New England Confederation in yellow