Biddle joined the  Lafayette Flying Corps in France on 8 April 1917.
He was assigned to Escadrille 73 as a private on 28 July 1917, under the command and mentorship of Albert Deullin.
 He was promoted to corporal on 2 June and to sergeant on 1 December.
 Biddle initially fought several indecisive combats with a Spad VII, but success evaded him until 5 December 1917.
Flying a SPAD XIII, he downed the Albatros two-seater of Leutnants Fritz Pauly and Ernst Sauter of FFA 45 despite a malfunction by both his Spad's machine guns.

Biddle transferred to the American 103d Aero Squadron on 10 January 1918 and was commissioned as a captain in the Aviation Section of the U.S. Army Signal Corps on 12 January 1918.
 He then and reverted to the Spad VII for his 12 April win over a Halberstadt CL.II over Corbeny.
He moved on to the 13th Aero Squadron (nicknamed "The Devil's Own Grim Reapers").

On 1 August, he shared his first two victories with William Howard Stovall, John Seerly, and H. B. Freeman.
He shot down three more enemy planes afterwards-his 5th official credit was a Rumpler CIV of Fliegerabteilung 46LB {pilot Eichler {POW} observer Gröschel {DOW} August 16, 1918.
 He was at one point entrusted with the only SPAD XII issued to Americans.
 He was promoted to the rank of major on 1 November  and was given command of the 4th Pursuit Group.
 He returned to the United States on 19 December and was discharged from the Army on 25 January.

In recognition of his service, the French awarded him both the Legion of Honor and the Croix de Guerre, and he received the American Distinguished Service Cross and the Belgian Order of Leopold II.

After the war, Biddle wrote a book entitled The Way of the Eagle.
Biddle joined the  Lafayette Flying Corps in France on 8 April 1917. He was assigned to Escadrille 73 as a private on 28 July 1917, under the command and mentorship of Albert Deullin.  He was promoted to corporal on 2 June and to sergeant on 1 December.  Biddle initially fought several indecisive combats with a Spad VII, but success evaded him until 5 December 1917. Flying a SPAD XIII, he downed the Albatros two-seater of Leutnants Fritz Pauly and Ernst Sauter of FFA 45 despite a malfunction by both his Spad's machine guns.
Biddle transferred to the American 103d Aero Squadron on 10 January 1918 and was commissioned as a captain in the Aviation Section of the U.S. Army Signal Corps on 12 January 1918.  He then and reverted to the Spad VII for his 12 April win over a Halberstadt CL.II over Corbeny. He moved on to the 13th Aero Squadron (nicknamed "The Devil's Own Grim Reapers").
On 1 August, he shared his first two victories with William Howard Stovall, John Seerly, and H. B. Freeman. He shot down three more enemy planes afterwards-his 5th official credit was a Rumpler CIV of Fliegerabteilung 46LB {pilot Eichler {POW} observer Gröschel {DOW} August 16, 1918.  He was at one point entrusted with the only SPAD XII issued to Americans.  He was promoted to the rank of major on 1 November  and was given command of the 4th Pursuit Group.  He returned to the United States on 19 December and was discharged from the Army on 25 January.
In recognition of his service, the French awarded him both the Legion of Honor and the Croix de Guerre, and he received the American Distinguished Service Cross and the Belgian Order of Leopold II.
After the war, Biddle wrote a book entitled The Way of the Eagle.
Charles J. Biddle (aviator)