Having participated in the Mediterranean theatre of World War II on behalf of Great Britain's British Indian Army, he opted for Pakistani citizenship and joined its military after the United Kingdom partitioned India in 1947, and helped in executing the covert infiltration in Indian Kashmir that sparked the war with India in 1965. After being controversially appointed to assume the army command in 1966, Yahya Khan took over the presidency from unpopular former dictator and elected President Ayub Khan, who was not able to deal with the 1969 uprising in East Pakistan, forced to resign by protests and offered him the office. Yahya Khan subsequently enforced martial law by suspending the constitution. Holding the nation's first nationwide elections in 1970, 23 years after independence, he delayed the power transition to victorious Sheikh Mujibur Rahman from East Pakistan, which further inflamed the civil violent unrest in the East, and authorized the East Pakistani authorities to violently suppress the rebellion. Around 10 million people took refuge in India. According to independent researchers, between 300,000 and 500,000 people died in what is today widely considered the 1971 Bangladesh genocide.