Appointed frigate captain, Brisson took command of the cruiser "Guichen". In this capacity, in 1915, he bombarded Ottoman forces near Musa Dagh and helped rescue 5,000 Armenians from genocide, conducting them to Port Said. In 1917, he was promoted head of the fourth section of the naval staff. In 1919, commanding the French naval forces in the Baltic Sea, he gave assistance to Latvia at the Battle of Riga.