June 19 – King Louis IX (the Saint) orders all Jews found in public, without an identifying yellow badge, to be fined ten livres of silver. He also confiscates goods from the Jewish population to fund the Eighth Crusade.
September – An Aragonese contingent under King James I (the Conqueror) sails from Barcelona to the Holy Land but is caught in a storm and badly damaged. One squadron reaches Acre, but later returns to Aragon.
Prince Edward (the Lord Edward) obtains the right to levy a twentieth of the value of the Church's wealth to finance the Ninth Crusade. That sum turns out to be insufficient, and Edward has to borrow to reach his target.[1]
Pierre de Maricourt, French mathematician and writer, performs a series of experiments with magnetic poles and proposes that a machine can be run forever in perpetual motion using the properties of magnets.