Career
He served as Apostolic Delegate to from 1933 to 1946, as Apostolic Nuncio to Chile from 1947 to 1953, and as Apostolic Nuncio to Argentina from 1953 to 1958. As Apostolic Delegate in Zanin did not have the rank of a Vatican ambassador to the Chinese government. He was nevertheless accorded the honours reserved for Ministers Plenipotentiary.
In 1939, After the Japanese conquest of Nanjing, Zanin remained in occupied territory, delegating to an American Franciscan his authority regarding the area held by the Chinese government, whose provisional capital was Chongqing.
In the occupied area, Catholics, like most people, adjusted to Japanese rule. In some locales, Catholics tried to work with the new authorities.
Zanin received complaints about missionaries who showed sympathy with the occupiers. On the other hand, after the killing, near a mission headquarters, of Chinese soldiers under Japanese command, some 60 Catholics, including a bishop, thought to have been involved were arrested with the intention of subjecting them to court-martial, but after intervention by the French diplomatic representatives were, except for one priest, released on condition that the bishop, who had previously refused to meet the Japanese authorities, be removed from his post.
Missionaries were interned, and some were killed.
Zanin mandated strict neutrality, asking the bishops to tell their priests "to avoid even the appearance of any action that.. could give an excuse for retribution against the mission residences.. Do not let the whole community perish on account of one person"s imprudence." This was unpopular with those who advocated a different stance. and led to formal representations from Chiang Kai-shek"s government. Claude Bowers, the American ambassador in Chile, described Zanin in the late 1940s as "a tall, slender man with graying hair.. highly cultivated, exceptionally able and brilliant".
In 1953, Zanin was transferred to the nunciature in Buenos Aires, where he died on 4 August 1958.
He thus witnessed the 1955 Revolución Libertadora that ended the rule of Juan Perón.