How was Emily Davison a Martyr?

Emily Davison, in full Emily Wilding Davison, (born October 11, 1872, Roxburgh House, Greenwich, Kent [now part of Greater London], England—died June 8, 1913, Epsom, Surrey [now part of Greater London]), British activist who became a martyr to the cause of women's suffrage when she entered the racetrack during the 1913