Why in News?

• Prime Minister Narendra Modi said the celebrations of the 75th year of Independence would be based on public participation and revolve around five themes — the freedom struggle and ideas, achievements, actions and resolve at 75.

How did August 15 become India’s Independence Day?

• At the 1929 Lahore session of the Indian National Congress, the Purna Swaraj declaration, or “Declaration of the Independence of India” was promulgated, and 26 January 1930 was declared as Independence Day at that time. 
• The Congress called on people to pledge themselves to civil disobedience and to carry out the Congress instructions issued from time to time until India attained complete independence
• The Congress observed 26 January as the Independence Day between 1930 and 1946.
• Lord Mountbatten had been given a mandate by the British parliament to transfer the power by June 30, 1948. Mountbatten thus advanced the date to August 1947.
• It provided for the end of the British rule in India, on August 15, 1947
• Following actual independence on August 15th, 1947, the Constitution of India came into effect on and from 26 January 1950; since then 26 January is celebrated as Republic Day.

Reference:

1. https://www.thehindu.com/news/national/public-participation-should-be-basis-of-celebrations-for-indias-75-years-of-independence-pm-modi/article34018882.ece