<P> To enable the initial breakthrough, Lieutenant Colonel Georg Bruchmüller, a German artillery officer, developed the Feuerwalze (de), (literally: rolling fire, rolling barrage) an effective and economical creeping barrage scheme . There were three phases: first, a brief bombardment on the enemy's command and communications (headquarters, telephone exchanges, etc .); then, destruction of their artillery; lastly an attack upon the enemy front - line infantry defences . Bombardment would always be brief so as to retain surprise . Bruchmüller's tactics were made possible by the vast numbers of heavy guns--with correspondingly plentiful amounts of ammunition for them--which Germany possessed by 1918 . </P> <P> In their turn, the Allies had developed defences in depth, reducing the proportion of troops in their front line and pulling reserves and supply dumps back beyond German artillery range . This change had been made after experience of the successful German use of defence in depth during 1917 . </P> <P> In theory, the front line was an "outpost zone" (later renamed the "forward zone"), lightly held by snipers, patrols and machine - gun posts only . Behind, out of range of German field artillery, was the "battle zone" where the offensive was to be firmly resisted, and behind that again, out of range of all but the heaviest German guns, was a "rear zone" where reserves were held ready to counter-attack or seal off penetrations . In theory, a British infantry division (with nine infantry battalions) deployed three battalions in the outpost zone, four battalions in the battle zone and two battalions in the rear zone . </P> <P> This change had not been completely implemented by the Allies . In particular, in the sector held by the British Fifth Army, which they had recently taken over from French units, the defences were incomplete and there were too few troops to hold the complete position in depth . The rear zone existed as outline markings only, and the battle zone consisted of battalion "redoubts" which were not mutually supporting (allowing stormtroopers to penetrate between them). </P>

Where was germany's initial offensive stopped during ww1