a show of courage or defiance
bravado - boldness
‘Bravado’ is a form of courage, but it does not have positive connotations. Typically it describes a swaggering display that is designed to convince others of your bravery and confidence, even if the truth is somewhat different. It can also refer to an unnecessary or dangerous show of courage that can cause more harm than good.
During the battle, Peter disobeyed orders and ran straight at the enemy in a reckless show of bravado. He nearly got the whole platoon killed!
Brenda strode into the meeting room to make her presentation, but it was false bravado. I could see she her hands shaking from nervousness.
In an act of foolish bravado, I told my boss that if she didn’t give me a raise I would quit. Unfortunately, she called my bluff.