Complex sentence: The long campaigning and hardships that Lucullus' troops had endured for years, combined with a perceived lack of reward in the form of plunder, and encouraged by Clodius Pulcher, led to successive mutinies amongst the legions in 68-67 BCE.
Split into simpler sentences: The long campaigning and hardships that Lucullus' troops had endured for years, combined with a perceived lack of reward in the form of plunder, became gradually insubordinate. Encouraged by Clodius Pulcher, this led to successive outbreaks of mutiny amongst the legions in 68-67 BCE.