When did Zia-ul-Haq become President?

General Muhammad Zia-ul-Haq became the sixth President of Pakistan on September 16, 1978.Zia-ul-Haq originally seized power in a bloodless military coup d'état on July 5, 1977, overthrowing the government of Prime Minister Zulfikar Ali Bhutto. Following the coup, he declared martial law and ruled as the Chief Martial Law Administrator.He allowed the incumbent President, Fazal Ilahi Chaudhry, to continue in office as a figurehead. When Chaudhry's term ended and he resigned in September 1978, Zia-ul-Haq assumed the office of President while retaining his other titles, cementing his position as the undisputed ruler of Pakistan until his death in an air crash in August 1988.