Jallianwala Bagh Massacre: ordered troops to fire on a peaceful, unarmed crowd gathered at Jallianwala Bagh to protest the Rowlatt Act and the arrest of leaders Saifuddin Kitchlew and Dr. Satyapal.

Hunter Committee: The British government appointed the Hunter Commission to investigate the massacre; while it censured Dyer, no penal or disciplinary action was taken against him (though he was removed from duty).