1946 the British governor's invitation to lead the Executive Council and became the de facto premier of Burma, the communists accused him of having sold out to the British and settled for a "sham independence". In November, the CPB was officially expelled from the AFPFL. In January 1947, Aung San and other AFPFL leaders such as Thakin Mya, Tin Tut, and Kyaw Nyein negotiated in London the independence for Burma. The British however made independence contingent upon the agreement of Burma's major ethnic minorities. Therefore, Aung San and other AFPFL colleagues among them Aung Zan Wai, Pe Khin, Bo Hmu Aung, Sir Maung Gyi, Myoma U Than Kywe and Sein Mya Maung took part in the Panglong Conference in February 1947 and convinced representatives from the Shan, Kachin, Chin and Kayah to support the negotiations for independence and join the future independent state of Burma. General elections for a constitutional assembly were held in April 1947, which the AFPFL won amidst an election boycott by the opposition, taking 173 of the 210 seats and running unopposed in over fifty constituencies. Aung San headed the constitutional assembly and was set to become Burma's prime minister, but was assassinated together with six other members of his cabinet on 19 July, a date commemorated as Martyrs' Day. U Nu succeeded Aung San as leader of the AFPFL and Premier of Burma. Independence and civil war Burma declared independence from Britain in January 1948, and the CPB went underground the following March after U Nu ordered the arrest of its leaders for inciting rebellion. Other groups also soon dropped out of the AFPFL to join the rebellion, not only the White-band faction of the People's Volunteer Organisation (PVO) formed by Aung San as a paramilitary force out of the demobbed veterans, but also a large part of the Burma Rifles led by communist commanders calling themselves the Revolutionary Burma Army (RBA). The AFPFL government had plunged into civil war with not only Burman insurgent groups but also ethnic minorities including the Karen National Union (KNU), Mon, Pa-O, nationalist Rakhine and the Mujahideen of Rakhine Muslims. The first post-independence general elections were held over several months in 1951 and 1952, with the AFPFL and its allies winning 199 of the 250 seats in the Chamber of Deputies. Parliamentary rule and split Although the AFPFL was returned to office again in the 1956 elections, the results