As World War II approached, the Sudan Defence Force assumed the mission of guarding the Sudanese frontier with Italian East Africa (present-day Ethiopia and Eritrea). During the summer of 1940, in what became the first moves of the East African Campaign, Italian forces invaded the Sudan at several points and captured the railway junction at Kassala and other villages along the border. However, while Port Sudan was raided by irregular Eritrean forces in August 1940, the SDF prevented an Italian advance on the Red Sea port city.