I enjoyed reading your reply. I like the "spherical cow" metaphor.

Foch was proven right. It must have been maddening for him to know the truth of the situation, but be over-ruled by popular sentiment toward ending a disastrous and suicidal war.

This makes me want to reconsider all of my own knowledge of course, because as your examples illustrate, it's possible that there is something worse than being wrong, and it is to not notice something important.