'Meksyk II' was the Polish first major operation by the Szare Szeregi (Grey Ranks) resistance group during the German occupation of Poland (26 March 1943).

Undertaken in Warsaw, the operation was otherwise known as 'Arsenal' after the Warsaw Arsenal, in front of which the action took place. The plan was designed to secure the liberation of the Polish underground leader Jan Bytnar, codenamed 'Rudy', who with his father had been arrested by the Gestapo. The force committed to the operation was 28 men led by Stanisław Broniewski, codenamed 'Orsza', and the plan’s originator and the commander of the attack group was Tadeusz Zawadzki, codenamed 'Zośka'.

The operation was completed successfully, and thus led to the release of Jan Bytnar and 24 other prisoners, including another underground leader, Henryk Ostrowski codenamed 'Henryk', and six women in an attack on the prison van which was taking the prisoners from Pawiak prison to the Gestapo headquarters at Szucha Avenue. Bytnar died four days later, however, as a result of the injuries he had already sustained as the hands of the Gestapo.