This outcome was unpopular among local Greeks, as a substantial Greek population existed on the Albanian side of the border. Among Greeks, northern Epirus was henceforth regarded as "terra irredenta". Local Greeks in northern Epirus revolted, declared their independence and proclaimed the Autonomous Republic of Northern Epirus in February 1914. After fierce guerrilla fighting, they managed to gain full autonomy under the terms of the Protocol of Corfu, signed by Albanian and Northern Epirote representatives and approved by the Great Powers. The signing of the Protocol ensured that the region would have its own administration, recognized the rights of the local Greeks and provided self-government under nominal Albanian sovereignty. The Republic, however, was short-lived, as when World War I broke out, Albania collapsed, and northern Epirus was alternately controlled by Greece, Italy and France at various intervals. Although short-lived, this state managed to leave behind a number of historical records of its existence, including its own postage stamps; see Postage stamps and postal history of Epirus.