Constantine's birth took place during the beginning of World War II. He was just a few months old when Fascist Italy on 28 October 1940 invaded Greece from Albania, beginning the Greco-Italian War. The Greek Army was able to halt the invasion temporarily and was able to push the Italians back into Albania. However, the Greek successes forced Nazi Germany to intervene. The Germans invaded Greece and Yugoslavia on 6 April 1941, and overran both countries within a month, despite British aid to Greece in the form of an expeditionary corps. Constantine and his family were evacuated from Athens, and spent the next four years in exile in Egypt and Cape Town, South Africa, (where his sister Irene was born) with his family. He returned to Greece with his family in 1946. King George died in 1947, and Constantine's father became the new king, making Constantine the crown prince.