فيصل الأول
In 1911 Abd al-Hadi, along with Rafiq al-Tamimi were founding members of the Paris-based underground al-Fatat ("the Young Arab Society") nationalist society, which was devoted to Arab independence and unity. He was among the organizers of the Arab Congress of 1913 in Paris. When Faisal I of Iraq arrived in Paris en route to London in December 1918 Ahmad Qadri located Abd al-Hadi introduced him to Faisal who appointed him as the head of the administrative office for the Arab delegation to the Paris Peace Conference, 1919.