On 23 March 1956, Pakistan changed from being a Dominion of the British Commonwealth and became an Islamic republic after framing its own constitution. Although the first general elections were scheduled for early 1959, severe political instability led President Iskander Mirza to abrogate the constitution on 7 October 1958. Mirza imposed martial law and handed power to the Commander-in-Chief of the Pakistan Army, General Muhammad Ayub Khan. After assuming presidency, President Ayub Khan promoted himself to the rank of Field marshal and appointed General Muhammad Musa Khan as the new Commander-in-Chief.