The Algerian victory in the referendum exasperates part of the army and the Algerian French. The most radical supporters of French Algeria found the OAS (Organization of the Secret Army), which commits attacks and grows stronger after the failure of the coup d'état of April 1961. The Algerian population remains mobilized; but De Gaulle refuses to cede the Sahara, rich in gas and oil and recent scene of the first French nuclear tests. In Paris, the peaceful march of October 17 becomes a massacre. Following negotiations between France and the GPRA, which conclude with the Evian agreements, a cease-fire comes into effect on March 19, 1962. The Algerian French, the soldiers and the harkis leave the country in haste.