Complex sentence: The first major force to be sent was a division under the command of Col Ambrosio Letelier, who was successful in his task, yet committed several abuses against the population, he was thus recalled to Lima and sent to Santiago to be court-martialed.
Split into simpler sentences: The first major force to be sent was a division under the command of Col Ambrosio Letelier, who was successful in his task, but committed abuses against the population. He was recalled to Lima and sent to Santiago to be court-martialed.