Leap-frogging

Leap-frogging was a familiar term during the First World War for a form of attack that was introduced in 1917 for penetrating deeply into the German fortified trench system. Successive lines of objectives, or limits of attack, were appointed to successive "waves" or attack formations of infantry. On the first wave capturing was the allotted objective, while it consolidated the position, the second passed through beyond it, or "leap-frogged" forward to capture the second objective ahead, and then in turn the third wave passed forward in like manner, following up the artillery barrage as it "lifted" and cleared the way for each advancing wave.