Historical examples of flinching away

I’m looking for historical examples of “flinching away,” so I can illustrate the concept to others and talk about motivated cognition and leaving a line of retreat and so on.

The ideal example would be one of motivated skepticism with grave consequences. Like, a military commander who shied away from believing certain reports because they implied something huge and scary was about to happen, and then the huge and scary thing happened and caused great damage. Something like that.

What examples can you think of?