Frente Leste (Portuguese for Eastern Front) was the name of the theater of Portuguese Armed Forces' anti-guerrilla operations in the East of Angola (by then a Portuguese overseas territory), during the Portuguese Colonial War (1961-1974). After the success of the Portuguese military in the Eastern front by 1973, it started to be known as the Eastern Zone, since guerrilla warfare episodes were nonexistent. Through economic and social promotion campaigns, including the construction of healthcare, education, sanitation, transport and security infrastructure, the construction of new villages, the training of new black military units like the Flechas, and the foreign units known as the Fiéis (former gendarmes from Zaire) and the Leais (refugees from Zambia), the Portuguese operations in the late stage of the anti-guerrilla war in Portuguese Angola, eradicated all the main sources of conflict in the territory.