On 29 September 1912, he was appointed to the chief of the 1st department (chief of operations) of the Vardar Army under the command of Ferik Halepli Zeki Pasha, formed within the Western Army. During the First Balkan War (8 October 1912 – 30 May 1913), after the defeat at the Battle of Kumanovo ( 23–24 October 1912), Fevzi wrote that the distributions of the Ottoman forces over a wide area gave initiative to the enemy and that mobilization and concentration plan was poorly designed and flawed. He also noted that there were great deficiencies in artillery, wireless, and air units. But he wrote that he had put the idea of creating a six-corps army of one hundred thousand men operation on interior lines from the Monastir (present day: Bitola) area. The Vardar Army retreated to Monastir.