By the mid-1960s the Pakistan experiment was in deep trouble. East Pakistan's elite had long struggled to get a better deal for themselves at the national centre – but now they understood that this was not going to happen. They came to the conclusion that only a movement for far-reaching regional autonomy could protect their interests.

Between 1962 and 1968 the Ayub regime was personified in the delta by a hostile provincial governor, Abdul Monem Khan, who persecuted and arrested political opponents, tightened control over the media and created an atmosphere of fear. He renewed the attack on the Bengali language – infamously banning songs by Rabindranath Tagore, the most revered poet, from Radio Pakistan – and thereby revived the politics of language. Now, celebrating 21 February or Tagore's birthday, or writing street signs and signboards in Bengali, became popular acts of defiance.

The unpopularity of the regime deepened further in 1965, when Pakistan started a war with India over Kashmir. During the six weeks of the war national sentiments ran high in East Pakistan but this proved to be the last flicker of the dying flame of national unity. East Pakistanis soon realised that there were hardly any armed forces in the province to defend them, leaving them completely exposed in the event of an Indian invasion. Even though India did not invade, the inhabitants of East Pakistan felt virtually cut off from West Pakistan.