It absorbed and replaced the Aeronautical Division, Signal Corps, and conducted the activities of Army aviation until its statutory responsibilities were suspended by President Woodrow Wilson in 1918.

[15][16][n 11] Beginning in August 1915, the 1st Aero Squadron spent four months at Fort Sill, Oklahoma, training at the Field Artillery School with eight newly delivered Curtiss JN-2s.

Eight Curtiss JN-3s[n 14] were disassembled at Fort Sam Houston on 12 March and shipped the next day by rail to Columbus, along with half of the squadron's motorized transportation: ten Jeffrey trucks, one automobile, and six motorcycles.

On 19 March, Pershing telegraphed Foulois and ordered the squadron forward to his advanced base at Colonia Dublán, 230 miles from Columbus, to observe for the 7th and 10th cavalry regiments.

Four that landed together at Ascensión (about halfway to Dublán) flew on to the advanced base in the morning, where they arrived an hour after the plane that had been forced to return to Columbus with engine trouble, and after another that had waited out the night on a road at Janos.

The 1st Aero Squadron flew a total of 540 liaison and aerial reconnaissance missions, traveling 19,553 mi (31,468 km) with a flight time of 345 hours 43 minutes.

No observations were made of hostile troops but the squadron performed invaluable services maintaining communications between Pershing's headquarters and ground units deep inside Mexico.

Their airplanes did not have sufficient power to fly over the Sierra Madre Mountains nor did they perform well in the turbulence of its passes, and missions averaged only 36 mi (58 km) distance from their landing fields.

The planes were nearly impossible to maintain because of a lack of parts and environmental conditions (laminated wooden propellers had to be dismounted after each flight and placed in humidors to keep their glue from disintegrating), and after just 30 days service only two were left.

Congress in a deficiency bill voted the Aviation Section an emergency appropriation of $500,000 (twice its previous budget), and although four new Curtiss N-8s[n 18] were shipped to Columbus, they were rejected by Foulois after six days of flight testing.

The European powers showed an immediate interest in promoting military aviation but the Army's general staff remained apathetic regarding development of aerial capabilities, as Captain Beck had charged the year before.

Officers who had testified against separation of aviation from the Signal Corps in August 1913 now were for it, marking the beginning of the movement that ultimately culminated in the creation of the United States Air Force 33 years later.

The commanding officer of the 1st Aero Squadron's 2nd Company at San Diego, Captain Lewis Edward Goodier, Jr., was seriously injured in a demonstration accident on 5 November 1914.

[30][n 21] They were aided by Goodier's father, Lieutenant Colonel Lewis Edward Goodier, Sr., Judge Advocate General of the Western Department in San Francisco, who also preferred charges against former squadron commander Captain William Lay Patterson for similar offenses,[n 22] charging that he had been awarded a rating of junior military aviator, and was drawing pay based on it, without being qualified to fly or being on flying duty.

[34] However the charge of malice allowed defense counsel wide latitude in its introduction of evidence,[35] and documents including official correspondence describing numerous incidents that confirmed Captain Goodier's original charges against Cowan became part of the court record, including support by the CSO of a pattern of retribution against officers on flying duty who fell in disfavor of Cowan.

[38] The second of these acting heads of division was Major William "Billy" Mitchell, a general staff officer who had testified before Congress in 1913 against transfer of aviation from the Signal Corps.

[24] While the Senate hearings were in progress and the 1st Aero Squadron encountered difficulties with its airplanes in Mexico, Scriven issued a statement accusing the young aviators of "unmilitary insubordination and disloyal acts" in an attempt to form an air service separate from the Signal Corps.

He also recommended that the age and marital status restrictions for pilots be removed to encourage older and therefore more experienced officers to volunteer for aviation duty.

Gen. Ernest Albert Garlington, the Inspector general, was appointed by Army Chief of Staff Gen. Hugh L. Scott to head a board of investigation into the Aviation Section.

The Garlington Board confirmed Goodier's allegations and also cited Scriven and Reber for failing to supervise the section adequately, holding them responsible for acquiring substandard aircraft.

[40] The Garlington Board's report, together with the Senate resolution and public criticism of the equipment used in Mexico, prompted Secretary of War Newton Baker to issue letters of reprimand to Scriven, Reber and Cowan.

[42] Lt. Col. George O. Squier was recalled from duty as military attaché in London and appointed Chief of the Aviation Section on 20 May, with orders to reform it literally from the ground up.

On 24 April 1916, the General Staff appointed a committee chaired by Col. Charles W. Kennedy to make recommendations for reform and reorganization of the Aviation Section.

[44] The Kennedy Committee recommended in July 1916 that aviation be expanded and developed, and that it be removed from the Signal Corps and placed under a central agency, in effect endorsing for the first time a call for a separate air arm.

The recommendation was quickly attacked by Assistant Army Chief of Staff Gen. Tasker Bliss, who branded the air officers supporting separation as having "a spirit of insubordination" and acting out of "self-aggrandizement".

[50] In the United States, the Aviation Section was nearly overwhelmed with the problems of rapid expansion to fight a modern war—the recruitment and training of pilots and mechanics, the production of airplanes, the formation and equipping of combat units, and the acquisition of air bases—while overseas a second force developed as part of the American Expeditionary Force, absorbing most of the experienced leadership of military aviation and taking over much of the expansion responsibilities except aircraft production.

Under pressure from the French, the Wilson administration set up a production plan to develop a force of 6,000 pursuit planes; 3,000 observation craft; and 2,000 bombers, a ratio established by Pershing, now commanding general of the AEF.

By the time of the United States entry into World War I in April, three squadrons (1st and 3rd in the U.S., 2nd in the Philippines) were in service, two (6th for Hawaii and 7th for the Panama Canal Zone) were organizing, and two (4th and 5th, to be based in the continental U.S.) had yet to receive personnel.

[52] Once formed, and prior to their deployment to Europe, Camp Taliaferro, north of Fort Worth, Texas, and several airfields near Toronto, Ontario, Canada were used by the British Royal Flying Corps (RFC) to perform flight training for the new aero squadrons.

[53] Upon their arrival in France, the St. Maixent Replacement Barracks was the primary reception center for new aero squadrons assigned to the Air Service American Expeditionary Force.