[nb 1] He overcame a fear of flying that resulted from his experiences with early flight, supervised the expansion of the Air Service during World War I, and became a protégé of then Brigadier General (later Colonel) Billy Mitchell.

He wanted assignment to the Cavalry but an inconsistent demerit record[12] and a cumulative general merit class standing of 66th out of 111 cadets resulted in his being commissioned on 24 June 1907, as a second lieutenant, Infantry.

In June 1909, the 29th Infantry relocated to Fort Jay, New York,[16] and en route to his new duty station by way of Paris, Arnold saw his first airplane in flight, piloted by Louis Blériot.

[24] After several more weeks of solo flying in Dayton to gain experience, Arnold and Milling were sent on 14 June to the Aeronautical Division, Signal Corps station established at College Park, Maryland, to be the Army's first flight instructors.

[nb 3] In August Arnold was at Marblehead, Massachusetts, with 1st Lieutenant Roy C. Kirtland conducting acceptance tests of the Burgess Model H, an enclosed-fuselage tandem-seat seaplane and the Army's first tractor (front-mounted propeller and engine).

The pair received orders to fly the new aircraft to Bridgeport, Connecticut, to participate in maneuvers but high winds forced them to land on Massachusetts Bay on 12 August.

Number 10, with 1st Lieutenant Follett Bradley as his wireless operator, successfully sent the first radio telegraph message, at a distance of 6 miles (9.7 km), from an aircraft to a receiver on the ground, manned by 1st Lt. Joseph O. Mauborgne of the Signal Corps.

[44] Between October and December 1916, encouraged by former associates, Arnold overcame his fear of flying by going up fifteen to twenty minutes a day in a Curtiss JN trainer, a much safer aircraft with a simpler flight control system than the Speed Scout of just four years' before.

When the military in Panama could not agree on a site, Arnold was ordered back to Washington, D.C., to resolve the dispute and was en route by ship when the United States declared war on Germany.

[nb 17] As Air Service Officer of the Ninth Corps area, he oversaw the first regular aerial patrols over the forested lands of California and Oregon to assist in preventing and suppressing wildfires.

After Mitchell was convicted on 17 December 1925, his supporters including Arnold continued to use Information Division resources to promote his views to airpower-friendly congressmen and Air Service reservists.

"[nb 20] Despite this setback, which included a fitness report that stated "in an emergency he is liable to lose his head",[65] Arnold made a commitment to remain in the service, turning down an offer of the presidency of the soon-to-be operating Pan American Airways, which he had helped bring into being.

[13][66][nb 21] Arnold made the best of his exile and in May 1927, his participation in war games at Fort Sam Houston, Texas, impressed Major General James E. Fechet, successor to Patrick as Chief of the U.S. Army Air Corps.

[71][nb 24] Arnold was slated for assignment to the Air Corps Training Center in San Antonio following graduation, but Brigadier General Lahm, the commander of the ACTC, strongly opposed it, possibly recalling their 1917 dispute.

[73] Arnold took command of the 1st Wing himself on 4 January 1933,[74] which flew food-drops during blizzards in the winter of 1932–33, assisted in relief work during the Long Beach earthquake of 10 March 1933, and established camps for 3,000 boys of the Civilian Conservation Corps.

[76][77][nb 25] In August 1932, Arnold began acquisition of portions of Rogers Dry Lake as a bombing and gunnery range for his units, a site that later became Edwards Air Force Base.

To encourage the use of civilian expertise, the California Institute of Technology became a beneficiary of Air Corps funding and Theodore von Kármán of its Guggenheim Aeronautical Laboratory developed a good working relationship with Arnold that led to the creation of the Scientific Advisory Group in 1944.

"[92] To that end he concentrated on rapid returns from R&D investments, exploiting proven technologies to provide operational solutions to counter the rising threat of the Axis Powers.

[44] In March 1939 Arnold was appointed to head the Air Board by Secretary of War Harry Woodring, to recommend doctrine and organization of Army airpower to the chief of staff.

[nb 35] Roosevelt refused to send the list to the Senate for confirmation because of Arnold's nomination, and his forced retirement from the service seemed imminent to both Stimson and Marshall.

Stimson and Harry Hopkins arranged for Arnold, accompanied by Major Elwood "Pete" Quesada, to travel to England for three weeks in April to evaluate British aircraft production needs and to provide an up-to-date strategic analysis.

On 9 March 1942, after the creation of the AAF failed to define clear channels of authority for the air forces, the Army adopted the functional reorganization that Arnold had advocated in October 1940.

Acting on an executive order from Roosevelt, the War Department granted the AAF full autonomy, equal to and entirely separate from the Army Ground Forces and Services of Supply.

[118][nb 41] With the strategic bombing crisis resolved in Europe, Arnold placed full emphasis on completion of the development and deployment of the B-29 Very Long Range (VLR) bomber to attack Japan.

However, theater commanders Douglas MacArthur, Chester Nimitz, and Joseph Stilwell all coveted the B-29s for tactical support, to which Arnold was adamantly opposed as a diversion from strategic policy.

In addition to being by nature intensely impatient, Arnold considered that his personal presence was required wherever a crisis might be, and as a result he traveled extensively and for long hours under great stress during the war, aggravating what may have been a pre-existing coronary condition.

[134][135][nb 42] On Guam, with knowledge of the approaching atomic bomb decision, he negotiated with Nimitz over the Navy's objections to basing the headquarters of the strategic air forces on the island.

Unlike George S. Patton, who had died suddenly in 1945 but had been independently wealthy, or his other colleagues who had taken positions in government, such as Marshall (appointed Secretary of State), Arnold had no source of income beyond his retirement pay and allowances.

[Hap Arnold was] a dedicated officer in a specialized field, ... and at the same time, a human being, a warm-hearted, loyal, mercurial, flamboyantly belligerent fellow who didn't care who he took on in battle.

Arnold delivers a short address and speaks with each of four pilots (actors Tod Andrews, Don DeFore, Ray Montgomery, and Dave Willock) as he pins on their wings.