Complex sentence: Powles 1928, p.124 Dismounted the squadrons advanced in turn, covered by their machine-guns, until at 15:00 they were within of the Turkish lines, they then were able to charge, with bayonets fixed, and captured the Turkish trench.
Split into simpler sentences: Powles 1928, p.124 Dismounted, the squadrons advanced in turn, covered by their machine-guns. At 15:00, when they were within of the Turkish lines, they were able to charge, with bayonets fixed, and captured the Turkish trench.