Here's the breakdown:
* Military origins: During the Middle Ages, soldiers would wear feathers in their hats as a way of displaying their accomplishments and rank. The more feathers they had, the more prestigious their victories and the higher their position.
* Symbolic meaning: The feathers became a symbol of achievement and honor.
* Evolution of the phrase: Over time, the literal act of wearing feathers in hats faded, but the symbolic meaning of "a feather in your cap" persisted.
Therefore, the idiom "a feather in your cap" means something that brings honor or pride, much like a feather in a medieval soldier's hat would represent their achievements.