Complex sentence: The party favored traditionalist assimilation into the political party system of Spain and when founded purchased the newspaper "Boletín Mercantil" to become the party's official organ for disseminating its conservative views.
Split into simpler sentences: The party favored traditionalist assimilation into the political party system of Spain. It purchased the newspaper "Boletín Mercantil" to serve as the party's official organ for disseminating its conservative views.