title: History of Sudan (1956–69)
context: On 1 January 1956 Anglo-Egyptian Sudan became the independent Republic of the Sudan. Before 1955, however, the government under Ismail al-Azhari had temporarily halted Sudan's progress toward self-determination, hoping to promote unity with Egypt. Despite his pro-Egyptian National Unionist Party (NUP) winning a majority in the 1953 parliamentary elections, however, Azhari realized that popular opinion had shifted against such a union. Azhari, who had been the major spokesman for the "unity of the Nile Valley", therefore reversed the NUP's stand and supported Sudanese independence. On December 19, 1955, the Sudanese parliament, under Azhari's leadership, unanimously adopted a declaration of independence that became effective on January 1, 1956. Azhari called for the withdrawal of foreign troops and requested the condominium powers to sponsor a plebiscite in advance.
question: When did Sudan become a republic?
answers: 1 January 1956