In 1939 the Poles basically dumped an absolutely massive amount of information they had worked out about enigma on the British and the French. The Poles had a working system to decrypt enigma from (I think) 1932 up to 1939 when the Germans added more rotors to the machines increasing the complexity significantly. The Polish techniques still worked with the new rotors but the additional complexity slowed them down a lot.

I maybe remembering this incorrectly but I think the Poles managed to construct machines logically identical to enigma machines (i.e. the same output for every input) based just on messages they'd intercepted (without ever seeing an actual enigma machine). They gave one of these machines to the French and one to the British.

The "Bombe" built in Bletchly park was directly inspired by the Polish "Bomba" machines.