The Allies built tanks to help them capture trenches. These tanks had tracks instead of wheels. So they could cross the mud and craters of no-mans -land with no problem. These tanks were also immune to machine gun fire and could smash through barbed wire. To assist the six Divisions involved in the attack, the tanks were broken up into small groups. They would lead the assault, destroying strong-points and allowing the infantry behind to push on and secure their objectives. A number failed to reach the start through breakdowns and some were unable to pass beyond it. When the attack commenced, only 15 were able to move into No-Mans Land.