What is the origin of the idiom "put on a brave face" and when to use it?

The origin of the idiom "put on a brave face" is rooted in the idea of maintaining a facade of strength, courage, or composure despite facing difficulties, challenges, or adversity. The phrase signifies the act of deliberately concealing one's true feelings, fears, or vulnerabilities behind a mask of bravery or confidence. It is often used to describe situations where individuals make a conscious effort to appear strong and optimistic outwardly, regardless of their internal struggles or fears.