Because of this, enemies in trenches were no longer always safe, and could constantly be fired upon. In some areas, artillery concentration was common, with several guns firing onto an area such as a line of trenches, each gun firing several rounds per minute for hours. Artillery barrages were also used before an infantry battle, to distract the enemy away from the place of attack, or the paths behind the lines were fired on so that enemy reinforcements could not safely reach the front lines.