 In 1975, partly for nationalist reasons and partly for fear of Moroccan expansionism, Mauritania invaded and annexed the southern third of the former Spanish Sahara (now Western Sahara) in 1975, renaming it Tiris al-Gharbiyya.However, after nearly three years of raids by the Sahrawi guerrillas of the Polisario Front, Mauritania's economic and political stability began to crumble.Despite French and Moroccan military aid, Polisario raids against the Zouerate railway and mines threatened to bring about economic collapse, and there were deep misgivings in the military about the Saharan adventure.