Complex sentence: Although they failed to achieve their objectives, by nightfall the ANZACs had formed a beachhead, albeit much smaller than intended, and in places they were clinging onto cliff faces with no organised defence system.
Split into simpler sentences: Although they failed to achieve their objectives, by nightfall the ANZACs had formed a beachhead, albeit much smaller than intended. In places they were clinging onto cliff faces with no organised defence system.