Well, firstly, it might sound surprising, but the primary aim of our leaders was not to gain complete freedom from British rule. The leaders at that time supported Dominion Status. This means, the Monarch of United Kingdom shall be the sole constitutional body of India.
It was in the year 1927, the idea of complete independence was proposed by Bhagat Singh along with Hindustan Republican Association, which was gaining a stronghold in Indian politics. The Congress was in favor of Dominion Status, while Singh and Republican Association proposed for complete independence. This was a major influence for the young blood of Indian National Congress like Jawaharlal Nehru and Subhash Chandra Bose. The Congress was asked to demand full Independence from the British government, but the demand made by the party did not pay any heed to them.
Thus, in the year 1928, Indian National Congress passed a resolution that demanded Dominion Status from British Government and offered one year time. But this was rejected by the British Government on the grounds that India was not at all ready for either home rule or the Dominion Status.
But this angered the Congress to a great extent and they when Nehru was elected as President in a session held in Lahore at 1929, the Congress finally opted for Complete Independence. A resolution was passed that stated; the last Sunday of January 1930 shall be celebrated as Independence Day. That day was 26the of Jan. The tri-color flag was hoisted on the Banks of river Ravi in Lahore.
This is how; 26th January is celebrated as the Republic Day of India.
