Upon his return to Tunis, after his exhausting trip across the Sahara to open a Third Front, Fanon was diagnosed with leukemia. He went to the Soviet Union for treatment and experienced some remission of his illness. When he came back to Tunis once again, he dictated his testament "The Wretched of the Earth". When he was not confined to his bed, he delivered lectures to Armée de Libération Nationale (ALN) officers at Ghardimao on the Algero-Tunisian border. He traveled to Rome for a three-day meeting with Jean-Paul Sartre who had greatly influenced his work. Sartre agreed to write a preface to Fanon's last book, The Wretched of the Earth.