المسيرة الخضراء
Moroccan government organized the Green March of some 350,000 Moroccan citizens, escorted by around 20,000 troops, who entered Western Sahara, trying to establish Moroccan presence. While, at first meeting just minor resistance by the Polisario, Morocco had later engaged in a long guerrilla warfare with the Sahrawi nationalists. During the late 1970s, After Moroccan pressure through the Green March of 6 November, Spain entered negotiations that led to the signing of the Madrid Accords by which it ceded unilaterally the administrative control of the territory to Mauritania and Morocco on November 14, 1975. The United Nations did not recognize the accord, considering Spain as the administrative power of the territory. In the fall of 1975, as a result of the Moroccan advance, tens of thousands of Sahrawis fled Morocco-controlled cities into the desert, building up improvised refugee camps in Amgala, Tifariti and Umm Dreiga.