Complex sentence: Bearing promises of British support, he created the first native secret society organized for such purposes, and more would henceforth be known as "party of independence", which included Castelli, Burke and major contributors of Vieytes's newspaper.
Split into simpler sentences: Bearing promises of British support, he created the first native secret society organized for such purposes. It would henceforth be known as "party of independence", including Castelli, Burke and major contributors of Vieytes's newspaper.