Chicken War or Hen War (Polish: Wojna kokosza) is the colloquial name for a 1537 anti-royalist and anti-absolutist rokosz (rebellion) by the Polish nobility.
The derisive name was coined by the magnates, who for the most part supported the King and claimed that the conflict's only effect was the near-extinction of the local chickens, which were eaten by the nobles gathered for the rokosz at Lwów, in Ruthenian Voivodeship.[1][2]
The magnates' choice of "kokosz"—meaning "an egg laying hen"—may have been inspired by a play on words between "kokosz" and the similar-sounding "rokosz".
The Chicken War was the first rokosz of the nobility in Polish history.[3]