The British themselves adopted a "carrot and stick" approach in recognition of India's support during the First World War and in response to renewed nationalist demands. The means of achieving the proposed measure were later enshrined in the Government of India Act 1919, which introduced the principle of a dual mode of administration, or diarchy, in which elected Indian legislators and appointed British officials shared power. In 1919, Colonel Reginald Dyer ordered his troops to fire their weapons on peaceful protestors, including unarmed women and children, resulting in the Jallianwala Bagh massacre; which led to the Non-cooperation Movement of 1920–22. The massacre was a decisive episode towards the end of British rule in India.