The 1966 military coup deposed Yaméogo, suspended the constitution, dissolved the National Assembly, and placed Lt. Col. Sangoulé Lamizana at the head of a government of senior army officers. The army remained in power for four years. On 14 June 1976, the Voltans ratified a new constitution that established a four-year transition period toward complete civilian rule. Lamizana remained in power throughout the 1970s as president of military or mixed civil-military governments. Lamizana's rule coincided with the beginning of the Sahel drought and famine which had a devastating impact on Upper Volta and neighboring countries. After conflict over the 1976 constitution, a new constitution was written and approved in 1977. Lamizana was re-elected by open elections in 1978.