Spain's war with the United Provinces and, in particular, the victories and atrocities of the Duke of Alba contributed to anti-Spanish propaganda. Sent in August 1567 to counter political unrest in a part of Europe where printing presses encouraged a variety of opinions (especially against the Catholic Church), Alba seized control of the publishing industry; several printers were banished, and at least one was executed. Booksellers and printers were prosecuted and arrested for publishing banned books, many of which were part of the Index Librorum Prohibitorum.