Complex sentence: A second gunner fired a burst of shots from the Lewis in the direction of the third section, then he swung the muzzle in the air to protect himself from the riflemen above, this was unsuccessful and he too fell dead beneath the gun.
Split into simpler sentences: A second gunner fired a burst from the Lewis in the direction of the third section, then he swung the muzzle in the air to protect himself from the riflemen above. This was unsuccessful and he too fell dead beneath the gun.