In November 1942 he visited Morocco to witness the American landings. Randolph encouraged the conversion of Vichy fighters to de Gaulle's army, submitting reports to Parliament on 23 February 1943. In May 1943 Randolph visited his father in Algiers, where he was celebrating the successful conclusion of the Tunisian Campaign. Randolph, along with his sister Sarah, accompanied his father to the Tehran Conference in November 1943. On the way back they quarrelled again about his failed marriage, which may have contributed to the serious heart attack which Winston Churchill suffered at Tunis. He visited his father, who was laid up with pneumonia, in Marrakesh in December 1943 (General Alexander gave him a lift on his plane). He was promoted to the temporary rank of major on 9 December.