Of course, this is the real key. How often in history have soldiers attacked at what they perceived to be 10% odds of winning? Extremely rarely. The first time they might attack out of ignorance of what awaits them. After that you either need fanatics, or the internal security police with massed machine guns behind them to make them go forward in such situations. Otherwise most commanders don't even bother to try, as certain death almost always means certain desertion. For game mechanics, however, it's probably only fair that the AI couldn't care less about the lives of it's soldiers. It gives the AI a fairer chance against the more flexible human mind, and the exploits that we humans use.
"I do not expect you to attack, I order you to die. In the time which passes until we die, other troops and commanders can come forward and take our places." - Ataturk to his soldiers who are out of ammo. It's extreme, but if the situation calls for it, a commander will send his soldiers to the death.