Complex sentence: Rather than fight, Fabius shadowed Hannibal's army and avoided battle, instead sending out small detachments against Hannibal's foraging parties, and maneuvering the Roman army in hilly terrain, so as to nullify Hannibal's decisive superiority in cavalry.
Split into simpler sentences: Rather than fight, Fabius shadowed Hannibal's army and avoided battle. While seeking to avoid battle, Fabius instead sent out small detachments against Hannibal's foraging parties, and always maneuvered the Roman army in hilly terrain, so as to nullify Hannibal's decisive superiority in cavalry.