[RERomine]

Depends on what you are referring to: real life or game terms.

In the game it's easy, you do what you need to. It's not that difficult to determine if a unit(s) will survive. In your example, you've pretty much said they wouldn't, so yes, you drop artillery. Heck, they might even survive because of the artillery, even if they take few casualties from it.

In real life, the same scenario is different. If the unit is calling artillery on their own position, it becomes a little easier. It's their call. In a third party situation, it's not nearly as cut and dried. Dropping artillery on your own men, no matter what their situation is bad for morale. This is everybody and not just the unit being sacrificed. A unit not "surviving" might mean they get captured. An artillery strike could kill these prisoners. It's one thing to do so by accident, but entirely different if you do it on purpose. I'm not saying you don't drop artillery in a real life situation, but the situation needs to be weighed very carefully to determine what you might gain verses what you might lose.