India’s freedom was achieved because of the INA and its legacy. The reason being, British was not ready to give India full independence, the best they would offer was Dominion Status, which they had been promising since 1917 and which the Congress leadership had almost accepted. However because of INA and the mounting anger and resentment among the armed forces, that triggered first the Naval revolt on 18 Feb 1946, the revolt in the Airforces over pay discrimination and postings and the revolt in the Signal Corps of Jabalpur, British realized that the armed forces were no longer immune from revolt. They were already shaken by the revolt in the British Indian Army that resulted in the formation of INA and their death defying battles against all odds in Imphal and Kohima sectors, their victory in Bishenpur and Arakan and their total commitment and dedication to the cause of Netaji. Even though they ridiculed them as JIFFs, they knew that these JIFFs had their brethren in the Indian Army who were inspired by their heroism, courage and had no longer the unswerving loyalty that was expected of them to fight the battles for the empire. Moreover racism in the Army was a foregone conclusion which even the British Army admitted. They knew that Indian Army was growing in confidence. They had seen the mighty British taking a beating in the WW2 against the Japanese, how the British lions were converted to rats against a far lesser no. of Japanese soldiers and how they had ran with tails between their legs from almost all of their erstwhile colonies in SE Asia. It was only with the aid of the British Indian soldiers and American airpower that they could finally win over Japan. So the British were no longer invincible and no longer the masters. The National political consciousness had risen and so the soldiers were no longer ready to sacrifice for the Empire.
This was the primary reason that led Britain to withdraw from India, and the main contribution of INA was that they hastened this fall through their indomitable courage and sacrifice. It was the story of INA that drove the nail, that led to the political resurrection of a moribund Congress and that, led to a temporary halt in the Communal propaganda of the League as the whole country was united in the name of Netaji Subhas Chandra Bose.