During the Nazi Occupation of Greece, Gonatas was imprisoned in the Haidari concentration camp for four months. After the German withdrawal, Gonatas was freed and re-entered political life. When he quarrelled with Themistoklis Sophoulis, the leader of the Liberal Party, he formed his own party, the Party of National Liberals (Κόμμα Εθνικών Φιλελευθέρων) which contested the 1946 general election in coalition with the conservative People's Party. Gonatas' party elected 30 members of Parliament. Having joined forces with the monarchist party, Gonatas committed himself to support the restoration of the monarchy in the 1946 plebiscite, which restored King George II to the throne.