Defensive Fire ?

[Nemo84]

Think of firing as a macro action, with the intent to stop the enemy from moving forward, there are consequences to trying to do that and it's defensive fire.

I played a number of test games with Dog Soldier of Bluecoat and in one I chose to fire as little as possible to reduce his ability to attrit me. Ultimately it reduced my losses but allowed him to advance further as I didn't activate my zones of control. Everything is a trade-off.

Can you explain this a bit further? How does firing stop the enemy from moving forward? How does it influence zone-of-control?