Complex sentence: When New York became English again in 1674, these eastern towns, whose people were Yankee by background, preferred to stay part of Connecticut, and Connecticut agreed, but the government of the Duke of York forced the matter.
Split into simpler sentences: When New York became English again in 1674, these eastern towns, whose people were Yankee by background, preferred to stay part of Connecticut. Although Connecticut agreed, the government of the Duke of York forced the matter.