Who founded Delaware and why?

After the failure of a Dutch colony in 1689, Delaware became "New Sweden," a colony by Swedish immigrants from 1638 until 1655, when it was taken over by the Dutch in New Netherland (New York). The Dutch themselves lost it to the English in 1664, and James, Duke of York leased his claim to William Penn, who had already established Pennsylvania farther up the Delaware and Schuylkill Rivers. Penn needed additional ocean ports for his colony's commerce, and the two colonies were governed together until 1708, when the "lower counties on the Delaware" acquired separate status.