[1] Born in Vilnius, during the short-lived Kingdom of Lithuania, Vilner's political life began as the leader of the Zionist group Hashomer Hatzair (Young Guard).

However, he soon grew disenchanted by what he viewed as a tendency in Zionist groups to dream of a Jewish homeland in Palestine, rather than change their current situation.

During the last years of the British mandate, Vilner became disenchanted with mainstream Zionist politicians, claiming that Jewish anti-Arab racism was comparable to the antisemitism he experienced in Vilnius.

In March 1946, Vilner testified to the Anglo-American Committee of Inquiry, claiming that partition strengthen the dependency of both states on outside aid and widen the gulf between Arabs and Jews.

Calling that day the darkest in Israel's history, Vilner demanded an immediate halt to the Israeli invasion of Arab-occupied lands.