Greece entered World War II on 28 October 1940, when the Italian army invaded 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. 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.