Complex sentence: Two of the central positions Quinn's and Courtnay's Posts had a steep cliff to the rear of the ANZAC trenches and in places the Turkish trenches were dug as close as from the Allied lines.
Split into simpler sentences: Two of the central positions, Quinn's and Courtnay's Posts, had a steep cliff to the rear of the ANZAC trenches. In places the Turkish trenches were dug as close as from the Allied lines.