Then a momentous event stunned the nation on 19 July 1947. U Saw, a conservative pre-war Prime Minister of Burma, engineered the assassination of Aung San and several members of his cabinet including his eldest brother Ba Win, the father of today's National League for Democracy exile-government leader Dr Sein Win, while meeting in the Secretariat. Since then 19 July has been commemorated since as Martyrs' Day in Burma. Thakin Nu, the Socialist leader, was now asked to form a new cabinet, and he presided over Burmese independence instituted under the Burma Independence Act 1947 on 4 January 1948. Burma chose to become a fully independent republic, and not a British Dominion upon independence. This was in contrast to the independence of India and Pakistan which both resulted in the attainment of dominion status. This may have been on account of anti-British popular sentiment being strong in Burma at the time.