Complex sentence: The sect's power grew in the late 1840s, initially by suppressing groups of bandits and pirates; persecution by Qing authorities spurred the movement into a guerrilla rebellion and then into widespread, bloody civil war.
Split into simpler sentences: The sect's power grew in the late 1840s, initially by suppressing groups of bandits and pirates. Persecution by Qing authorities spurred the movement into a guerrilla rebellion and then into widespread, bloody civil war.