Before long, the increased taxes and oppression that came with the re-imposition of caliphal authority in Egypt became deeply unpopular, and a rebellion broke out in the Hawf district in Lower Egypt. Isa responded to the uprising by sending his chief of security, his son Muhammad, with an army to fight the Hawfis. Muhammad, however, suffered a major defeat at Bilbays in April 829 and barely escaped with his life, while most of his men were killed.