Complex sentence: Meanwhile, at dusk, the 1st Light Horse Brigade began its descent moving down the Wadi Qumran to the Jordan Valley following a goat track which fell in to get into position to attack Nebi Musa from the rear.
Split into simpler sentences: Meanwhile, at dusk, the 1st Light Horse Brigade began its descent. They moved down the Wadi Qumran to the Jordan Valley, following a goat track which fell in to get into position to attack Nebi Musa from the rear.