Campaign for Pakistan.

Main article: Pakistan Movement

Chaudhry Khaliquzzaman seconding the Resolution with Jinnah and Liaquat presiding the session.

At a League conference in Lahore in 1940, Jinnah said:

Hindus and the Muslims belong to two different religions, philosophies, social customs and literature.... It is quite clear that Hindus and Muslims derive their inspiration from different sources of history. They have different epics, different heroes and different episodes.... To yoke together two such nations under a single state, one as a numerical minority and the other as a majority, must lead to growing discontent and final destruction of any fabric that may be so built up for the government of such a state.

In response to Jinnah's speech, the All-India Jamhur Muslim League (AIJML) was formed to counter the move of Jinnah on his support for Sir Syed's two-nation theory and to oppose the creation of Pakistan. The Raja of Mahmoodabad was elected its president and Maghfoor Ahmad Ajazi was its first general secretary. Perhaps it was the first split of Muslim League on ideological ground. This party however merged with Indian Congress latter on to strengthen its views on partition.
At Lahore the Muslim League formally recommitted itself to creating an independent Muslim state, including Sindh, Punjab, Baluchistan, the North West Frontier Province and Bengal, that would be "wholly autonomous and sovereign". The resolution guaranteed protection for non-Muslim religions. The Lahore Resolution, moved by the sitting Chief Minister of Bengal A. K. Fazlul Huq, was adopted on 23 March 1940, and its principles formed the foundation for Pakistan's first constitution. Talks between Jinnah and Gandhi in 1944 in Bombay failed to achieve agreement. This was the last attempt to reach a single-state solution.

First Session of All India Jamhur Muslim League

In the 1940s, Jinnah emerged as a leader of the Indian Muslims and was popularly known as Quaid-e-Azam (lit. Great Leader). In the Constituent Assembly of India's elections of 1946, the Muslim League won 425 out of 476 seats reserved for Muslims (and about 89.2% of Muslim votes) on a policy of creating an independent state of Pakistan, and with an implied threat of secession if this was not granted. Congress, led by Gandhi and Nehru remained adamantly opposed to dividing India.
However, 1947 saw violent and bloody battles caused due to the communal clashes between the two communities in India. Millions of people migrated from India to Pakistan and vice versa. The situation continued to be tense even after the governments of the two nations were formed.
The partition seems to have been inevitable after all, one of the examples being Lord Mountbatten's statement on Jinnah: "There was no argument that could move him from his consuming determination to realize the impossible dream of Pakistan."