Is this likely? For a character I'm writing.?

In a war story I'm writing, I want to have one of the characters be a three-star general in the army. However, a friend of mine told me that the beginning is unlikely because a three-star general wouldn't be lying in bed, next to his wife, and worrying about the ensuing war on the horizon, and whether he would be sent off to it. He would be at a military headquarters already. Is that true? What about, say, a one-star general? How are the stars earned, anyway? Thank you for your answers.