"The men advanced cautiously. They formed up. Their company commanders waved them on. Then the artillery increased its range, and the men moved forward more quickly. Running in a half crouch, they stayed fifty yards behind the advancing line of falling shells.
"This was called a creeping barrage. Gueudecourt was the first place the Allied armies used it. In previous months, the French had employed the tactic with some success. It was intended to get infantry to trenches and machine-gun nests before the enemy had recovered from heavy shelling. The artillery fire moved in front of the advance like a screen. It was sometimes called a curtain attack."