While Pope, Bl. John XXIII began a dialogue with the Soviet Union that led to the eventual fall of the Iron Curtain during the pontificate of his successor John Paul II, both of whom will be canonized April 27.

In 1961, the birthday of "Good Pope John" became the occasion for the first communication between the Soviet Union and the Vatican since the October Revolution of 1917.

Semen Kozyrev, the Soviet ambassador to Italy, sent birthday greetings to the Pope which read:  "On behalf of Khrushchev, I have been entrusted with the task of communicating to His Holiness, Pope John XXIII, on the occasion of his 80th birthday, my congratulations and sincerest wishes for good health and success in the continuation of the noble aspiration of contributing to the strengthening and consolidation of peace on earth and the solution of international problems through candid pronouncements."

John XXIII wrote a reply by hand, on paper headed with his coat of arms; the reply was returned to Kozyrev through Archbishop Carlo Grano, who was apostolic nuncio to Italy.

"His Holiness Pope John XXIII," his reply read, "extends his thanks for the wishes and expresses for your behalf and for the entire Russian people also, his cordial wishes for the growth and consolidation of universal peace, through the mutual understanding of human fraternity: for this he fervently prays."

This exchange opened a channel of communication between the states, and when the Cuban missile crisis emerged the following year, John XXIII used it to send a message to the Soviet Union, as well as to the U.S.

The message concluded by begging "all governments not to remain deaf to this cry of humanity. That they do all that is in their power to save peace. They will thus spare the world from the horrors of a war whose terrifying consequences no one can predict. That they continue discussions, as this loyal and open behaviour has great value as a witness of everyone's conscience and before history. Promoting, favouring, accepting conversations, at all levels and in any time, is a rule of wisdom and prudence which attracts the blessings of heaven and earth."

The message was delivered to both the American and Soviet embassies, was broadcast on Vatican Radio, and was also published on the front page of Pravda, the official voice of the Soviet communist party.

Bl. John XXIII's diplomacy also resulted in the release of Cardinal Josyf Slipyj, Ukrainian Archbishop of Lviv, from a gulag Jan. 25, 1963.

Cardinal Slipyj had been arrested by the Soviets in 1945, and spent much of his time since then in Siberian gulags.

The Holy See had long advocated for his release, but it was not until into John XXIII's pontificate that the cardinal was released by Khrushchev.

A month later, Alexei Adzhubei, editor of the Soviet government's newspaper Izvestia and Khrushchev's son-in-law, was visiting Rome and wished to meet the Pope.

Even though many Vatican prelates were against the meeting, on the advice of Cardinal Siri of Genoa, Bl. John XXIII chose to meet Adzhubei and his wife, Rada, March 7, 1963.

This series of events paved the way for Paul VI's policy of Ostpolitik, by which he engaged in dialogue with officials from the Warsaw Pact to improve conditions for Christians in those nations.