During the Second World War, Florence was the scene of a major rescue mission in a joint effort by Jewish leaders and members of the Catholic Church. Described in testimony of one of the Catholic rescuers as "the soul of this 'activity of love,' ” Dalla Costa guided, initiated and encouraged Catholic clergy to participate in the network. He recruited rescuers from among the clergy, supplied letters to his activists so they could go to heads of monasteries and convents to ask them to shelter Jews, and sheltered fleeing Jews in his own palace for short periods until they were taken to safe places.
Following the December 1943 arrest of the Jewish activist members of the network, the church under Dalla Costa continued in its rescue efforts, despite the arrest and torture of some clergy. Through its joint work, the network managed to save hundreds of local Jews as well as Jewish refugees from other countries.
The title Righteous Among the Nations is bestowed on those "few who helped Jews in the darkest time in their history." A public commission, headed by an Israeli Supreme Court justice, examines each case and is responsible for granting the title. Those recognized receive a medal and a certificate of honour. The cardinal's name will be engraved on the Wall of Honour in the Garden of the Righteous at Yad Vashem.
Officials at Yad Vashem said they have been unable to identify any next of kin for the cardinal, and so the medal and certificate will remain at Yad Vashem.