New Delhi, Sep 16: Expressing condolence on the demise of Marshal of Air Force Arjan Singh, Prime Minister Narendra Modi on Saturday said that India will never forget his "excellent leadership" in the 1965 war with Pakistan. "India mourns the unfortunate demise of Marshal of the Indian Air Force Arjan Singh. We remember his outstanding service to the nation. India will never forget the excellent leadership of Marshal of the IAF Arjan Singh in 1965, when the IAF saw substantial action," Modi said in a series of tweets. Modi also remembered the late Marshal's "soldier discipline", saying that despite his ill health, Arjjan Singh tried to get up to salute the Prime Minister when he met him some time back, even though he tried to dissuade him. "Arjan Singh's determined focus on capacity building in the IAF added great strength to our defence capabilities. My thoughts are with his family and those mourning the demise of a distinguished air warrior and fine human, Marshal of the IAF Arjan Singh," Modi said. Singh passed away at the Army Research and Referral Hospital here at 7.47 pm. He was admitted to the Intensive Care Unit (ICU) after suffering a massive heart attack in the morning.