 I'm Lieutenant Colonel David Williams. I'm the commander of 1st Battalion, 502nd Infantry Regiment, 2nd Brigade Combat Team, 101st Airborne Division, AirSault. So trench warfare is significant because when you think about large-scale combat operations, a force that's on the offense will come to a culmination point. So typically you'd see a trench dug into the ground as part of a defensive network. So it could be for a prolonged defensive operation or it could be a hasty defense. But either way, the trench is really designed to offer protection, to protect either supplies, resupply, and protect fighting forces as we regenerate combat power or to set in a defense and absorb some of the enemy's offensive capability in the effort to deplete them, to get them to a position where we can then counterattack and resume the offensive. It's going to be significant in future warfare. We're going to face the urban fight. As you can see in the background, that's going to be part of what we do. We know that, but we're also going to move to more of a maneuver warfare in open spaces using micro terrain. And the trench gives you that significant capability that you can protect yourself. But on the offensive side, we know that the enemy is going to do the same. And so we have to train to be able to assault through obstacle networks into trenches and clear them of the enemy so that we can control that terrain as we transition back to the offense.