The Jallianwala Bagh massacre (April 13, 1919) was directly preceded by the passage of the Rowlatt Act in March 1919. This act allowed detention without trial, triggering nationwide protests including the one at Jallianwala Bagh. The Partition of Bengal (1905) and Simon Commission (1927) were separated by many years. Gandhi's first Satyagraha was in South Africa (1906-1914), not immediately before.