As a variation on the circling fight, the Lufberry Circle of World War I also found favour in World War II, though pilots had to be careful in their decision to use the tactic: on one occasion RAF single-engined fighters managed to get inside a circle of Messerschmitt Bf 110 twin-engined fighters, and by circling in the opposite direction to the German aircraft, were able to down a number of them with hardly a shot fired in return by the Bf 110s, whose forward firing guns could not be brought to bear, and whose single flexible machine-guns had little more than nuisance value. So it was essential in a Lufberry Circle to ensure that one\'s adversary could not insinuate himself into the circle, or disaster was almost inevitable.