After the assassination of Ziaur Rahmanon 30 May, 1981, Ershad supported Abdus Sattar, the Vice-President who succeeded Zia as President and ordered the army to suppress the coup attempt.Ershad however maintained loyalty to the new President Abdus Sattar, wholed the Bangladesh nationalist Party to victory in elections in 1982.H.M.Ershad even alloted a house to Mrs Khaleda Zia and her two sons when he took over as Chief Martial law Administrator (CMLA). Choudhury speculates that Ershad wanted to assume power but decided to bide his time.Zia was popular, Sattar was respected even admired so before placing his demand, he began to claim that that the politicians were corruptand were "ruing the country" Under presure from high ranking army commanders for the military to take over the reins of the State Ershad toppled President Sattar in a bloodless coup on 24 March, 1982 and Proclaimed himself Chief Martial Law Administrator (CMLA) with Justice A.F.M.A. Choudhury as nominal presidentand latef 11 Dec 1982 took over the charge as President.He announced his preference for Shari'ah law. On March 14, 1983 Khaleda Zia of the BNP and Sheikh Hasina of the Awami League were both arrested. Subsequently they were released after few days. In March 1985, Ershad held a referendum on his presidency , claiming a positive vote of 94.15 %. Though there were allegations of fraud . Two months later, in a largely uncoctested election for local council chairs, Ershad's newly created Jatyo Party swpt the board.In January 1986, he lifted restrictions on political parties and announced a parliamentary election. This was held at the end of the year but due to irregularities repolling of some constituencies were held. BNP boycotted but Awami league and other parties participated. In the result AL won 76 seats, Jatyo party of Ershad, won 153, smaller parties won 39, and independents got 32.The third largest party was Jamaat-e-islam who got 10 seats. Communists won 5 seats.
Sheikh Hasina became official leader of the opposition but rarely she attended parliament, which was by-passed by Ershad whenever possible. His system of Governance relied on the secretaries of the various Ministries with "little political consultation with the Ministers". Three measures that parliament did were controversial. i) In Aug 1986, Ershad resigned as army chief of staff in order to stand for election as President. This time , both the main opposition Party BNP and AL, boycottedthe election.which Ershad easily won. In Nov 1986, Parliament voted to legalise Ershad's Presidency from this assumption of powers.
Two controversial measures did gain parliamentary approval. In July 1987, an Act gave the military representation on local councils. In June 1988, the constitution ws amended to establish Islam as the state religion, abandoning state secularism. This was mainly to to strengthen Bangladesh's standing in the Muslim World. In fact opposition came from a broad spectrum, including women, the main opposition parties and non-muslim Bangladeshis. Late 1988 and early 1989 saw some of the worst floods on record, and political activity took second place to relief work. Ersahd had been praised for efficient handling of the this emergency.