Nation is paying tribute to freedom fighter Udham Singh on his 70th Martyrdom Day today. A number of functions have been organised to mark the occasion.In Punjab, a state-level 'Shaheedi Samagam' is being organised at his native village 'SUNAM' in Sangroor District to pay tributes to the great revolutionary. Udham Singh avenged the massacre of Jallianwala Bagh by killing Lt. Governor of British ruled Punjab, General O'Dyer in London.