sentences:  Infantry officers were also taught his methods and there were joint infantry-artillery exercises with live ammunition, with advances shielded by the creeping barrage.The first attack, Operation Michael, began with a barrage of shells in five hours, almost a second.Defying instructions, Bruchmüller eliminated preliminary registration by firing from the map and then directed the artillery during the next attack at the Battle of the Lys on Flanders, where the artillery had not yet been trained in the Pulkowski method.