Members of the Islamic State close in on a stranded member of the Iraqi Army. The lone Soldier gives them a lesson in the basics of CQB while making his last stand.

What you're looking at in this video is the point-of-view of an Islamic State fighter as his group closes in on a stranded Iraqi Soldier trapped in a building by himself. It's very clear from the footage that the ISIS fighter has little-to-no professional warfighting training, as all of his actions are clearly done from instinct rather than hard-wired training. An ounce of training in military operations in urban terrain would have told this Islamic State fighter that standing in a doorway more than once while you know the enemy is on the other side is a bad idea.

Anyways, if we're going to show you why the fatal funnel is called the fatal funnel, I couldn't think of a better group of individuals to be on the receiving end of this lesson. A doorway or hallway inside of a building is the most dangerous place that you can be inside of a house during a gunfight. There is only one way for the rounds to travel, and that's directly through that passage. It's also the only way to enter and maneuver through the house, so it's the point of friction that most warfighters are going to struggle with when entering a house to clear it out.

CQB, or close quarter battle, is generally known as a last resort simply because of that fact. If there is no reason for you to make entry into a house with an enemy inside, it's usually best to clear the building from the outside using explosive ordinance. Entering the house should be your last resort, and it should only be done if there are hostages inside that you need to save, or possible friendlies inside that you want to avoid killing at all costs. Even still, before breaching into a house, it's common practice to use less-lethal means of breaching the house such as flash-bang grenades to stun your enemy and give you the upper-hand.

These Islamic State fighters learned this the hard way, and at the very least our cameraman here will never have an opportunity to remediate on his training.