Complex sentence: The continued advance south by the Australians spread them thin on the ground and due to concerns that their western flank was exposed led to the 2/17th Infantry Battalion being sent along the Sattelberg track to deflect any Japanese thrusts from there.
Split into simpler sentences: The continued advance south by the Australians spread them thin on the ground. Due to concerns that their western flank was exposed, the 2/17th Infantry Battalion was sent along the Sattelberg track to deflect any Japanese thrusts from there.