Complex sentence: A human soldier from before the Federation's formation, Edison became disillusioned with his life and purpose following the establishment of peace with humanity's enemies, and when he and his crew were stranded in the nebula, he became convinced he had been cast aside.
Split into simpler sentences: A human soldier from before the Federation's formation, Edison became disillusioned with his life and purpose following the establishment of peace with humanity's enemies. When he and his crew were stranded in the nebula, he became convinced he had been cast aside.