On the Western Front, the main objective of tunnel warfare was to place large quantities of explosives beneath enemy defensive positions. When it was detonated, the explosion would destroy that section of the trench. The infantry would then advance towards the enemy front-line hoping to take advantage of the confusion that followed the explosion of an underground mine. It could take as long as a year to dig a tunnel and place a mine. As well as digging their own tunnels, the military engineers had to listen out for enemy tunnellers. On occasions miners accidentally dug into the opposing side's tunnel and an underground fight took place. When an enemy's tunnel was found it was usually destroyed by placing an explosive charge inside.