During World War II, he collaborated with the Journal de Genève and other newspapers across Europe.
In 1944, his book Préliminaires de la guerre à l'Est (Preliminaries of the War in the East) was published under the author name of Grégoire Gafenco at the Egloff publishing house in Fribourg.

After the war, Gafencu moved to Paris.
He then published his second book, Last Days of Europe (Derniers jours de l'Europe, Egloff, Fribourg, 1946), in which he described his voyages across Europe in 1939 and 1940.
In the preface he claimed that "the world made a war to kill influence zones and we must make a peace to kill them for a second time".

In 1947 he was invited by Yale University Press to the United States for a series of conferences; at that time, he lectured at New York University.
He began to form groups that would militate for a European Movement, i.e., a federalization of the European states, in which Romania would also be included.
He participated at the founding of the Free Europe Committee and he organized each Tuesday evening in his apartment on Park Avenue, New York City a series of meetings called Tuesday Panels in which current events were discussed.

He was a member of the Romanian National Committee (1949–1952) and was one of the founders of the Free Romanian League.

Gafencu was awarded Order of the White Eagle and other decorations.
During World War II, he collaborated with the Journal de Genève and other newspapers across Europe. In 1944, his book Préliminaires de la guerre à l'Est (Preliminaries of the War in the East) was published under the author name of Grégoire Gafenco at the Egloff publishing house in Fribourg.
After the war, Gafencu moved to Paris. He then published his second book, Last Days of Europe (Derniers jours de l'Europe, Egloff, Fribourg, 1946), in which he described his voyages across Europe in 1939 and 1940. In the preface he claimed that "the world made a war to kill influence zones and we must make a peace to kill them for a second time".
In 1947 he was invited by Yale University Press to the United States for a series of conferences; at that time, he lectured at New York University. He began to form groups that would militate for a European Movement, i.e., a federalization of the European states, in which Romania would also be included. He participated at the founding of the Free Europe Committee and he organized each Tuesday evening in his apartment on Park Avenue, New York City a series of meetings called Tuesday Panels in which current events were discussed.
He was a member of the Romanian National Committee (1949–1952) and was one of the founders of the Free Romanian League.
Gafencu was awarded Order of the White Eagle and other decorations.
Grigore Gafencu