AG346 was the very first operational Mustang Mk.I. During this mission, it was hit by intense antiaircraft fire northeast of Gacé. The Mustang’s pilot, Flight Lieutenant Denis Clark, 119758, Royal Air Force Volunteer Reserve, bailed out. He landed safely, but was captured and taken to a German prisoner of war camp at Les Hogues, a small community east of Rouen.
Flight Lieutenant Clark, along with four other prisoners of war,² was shot and killed at the camp on the afternoon 25 August 1944. A Court of Enquiry held in August 1945 found that the five men had been murdered by SS-Obersturmfürer Eugen Gutemann. Gutemann had been captured in Italy on 28 April 1945 and was held as a prisoner of war by the American forces. It is not known if he was ever brought to trial.
Denis Clark was born 17 December 1918 at Stockton-on-Tees, County Durham, England. He was the son of Sydney Clark, an electrician in the chemical industry, and Minnie Gertrude Ritchie.
In 1939, Clark was employed as a civil service clerk. He resided at 3 Crayke Road in Stockton, with his parents and maternal grandmother.
He was married to Miss Beth Ayre of Seaton, County Durham, possibly in July 1942.
Clark entered the United States at Buffalo, New York, on 16 July 1941, having traveled from Toronto, Ontario, Canada. He was trained as a pilot at the Southern Aviation School, a military contract primary flight school in Camden, South Carolina, United States, beginning in July 1941. He was one of 297 RAF pilots to train there between 7 June 1941 and 16 February 1942.
On 7 February 1942 Temporary Flight Sergeant Denis Clark 945260 was promoted to the rank of Pilot Officer on probation (Temporary) 119758.
On 1 October 1942, Pilot Officer (prob.) Denis Clark was promoted to Flying Officer on probation (war substantive).
Flying Officer Clark was later promoted to the rank of Flight Lieutenant. (Date not determined)
Flight Lieutenant Denis Clark, RAFVR, was buried at Les Hogues Communal Cemetery, along with the other four victims. His head stone is engraved
GREATER LOVE HATH NO MAN THAN THIS.
THAT A MAN LAY DOWN HIS LIFE FOR HIS FRIEND.
On 10 September 1945 a warrant was issued as a gratuity for the representatives of deceased officers in the amount of £172/13/7.
The very first operational North American Mustang, AG346 (North American Aviation serial number 73-3099) was the second airplane to come off the assembly line at Inglewood, California. North American test pilot Robert Creed Chilton took it for its first flight 3 July 1941. It was the first Mustang Mk.I to be equipped with its full armament.
During flight testing of the first Mk.I, AG345, Chilton and other test pilots heard a banging sound. This was determined to be a resonance in the carburetor intake tract. Also, at high angles of attack, air flow into the intake was decreased. The intake was lengthened. The resonance stopped and air flow to the carburetor was improved.
After flight testing by North American’s test pilots and Royal Air Force fighter pilots Wing Commander Chris Clarkson and Squadron Leader Michael N. (“Red Knight”) Crossley, AG346 was disassembled and crated, then shipped from the port of Long Beach, California, through the Panama Canal and on to England, arriving at Liverpool, 24 October 1941. It was taken to the Lockheed facility at Speke Aerodrome (now, Liverpool John Lennon Airport, LPL) where it was reassembled and put through additional performance and flight tests. Up to 20,000 feet (6,096 meters), AG346 was faster than any other British fighter then in service. A Mk.II reflector gun sight was installed (the same type used in the Supermarine Spitfire), as well as a British VHF radio.
AG346 was publicly displayed for the British news media at Speke Aerodrome on 5 December 1941.
AG346 was then assigned to an operational RAF fighter squadron. It served with Nos. 225, 63 and 26 Squadrons before being assigned to No. 41 Operations Training Unit. AG346 was returned to operations with No. 16 Squadron, and finally, No. 168 Squadron.
North American countered with a proposal to design a completely new and superior fighter around the P-40’s liquid-cooled Allison V-12 engine, and to begin production in no more time than it would take to get a P-40 production line up and running. The Purchasing Commission agreed, and with a letter of understanding, North American began work on the NA-73X on 1 May 1940. They were to produce 320 fighters before 30 September 1941—approximately 50 per month—at a total price of $14,746,964.35.
Designed by a team led by Edgar Schmued, the prototype North American Aviation Model NA-73X, serial number 73-3097, registered NX19998, was completed 9 September 1940. After a delay waiting for the Allison V-1710 to arrive, the prototype made its first flight 26 October 1940 with free lance test pilot Vance Breese in the cockpit. This was only 179 days since work began on the project.
In a contract amendment dated 9 December 1940, the British Purchasing Commission directed that the NA-73 would be identified by the name, “Mustang.”
The Mustang Mk.I (NAA Model NA-73) was a single-place, single-engine fighter primarily of metal construction with fabric control surfaces. It was 32 feet, 3 inches (9.830 meters) long with a wingspan of 37 feet, 5/16-inches (11.373 meters) and height of 12 feet, 2½ inches (3.721 meters). The airplane’s empty weight was 6,280 pounds (2,849 kilograms) and loaded weight was 8,400 pounds (3,810 kilograms).
This engine gave the Mustang Mk.I a maximum speed of 382 miles per hour (615 kilometers per hour) and cruise speed of 300 miles per hour (483 kilometers per hour). The service ceiling was 30,800 feet (9,388 meters) and range was 750 miles (1,207 kilometers).
The Mustang Mk.I was equipped with four Browning AN-M2 .50-caliber machine guns, with one in each wing and two mounted in the nose under the engine and four Browning .303 Mk.II machine guns, two in each wing. The airplane carried 300 rounds of ammunition for each of the .50-caliber guns. Each of the inboard .303s were supplied with 932 rounds; and the outboard .303s, 814 rounds, each.³
The British would recommend that the Allison engine be replaced by the Rolls Royce Merlin V-12. This became the Mustang Mk.III and the U.S.A.A.F. P-51B. Eventually, over 15,000 Mustangs were built, and it was a highly successful combat aircraft.
Today, after 85 years, the Mustang is one of the most recognizable of all airplanes.
¹ No. 168 Squadron was a reconnaissance unit. Its motto was Rerum cognoscere causas (“To know the cause of things”)
² Warrant Officer Griffin James Young R85855, Royal Canadian Air Force, a Spitfire pilot who had been shot down 13 August 1944; Lead Bombardier Jack Martin 976272, 65th Anti-Tank Unit (The Norfolk Yeomanry), Royal Artillery, captured 21 August; an unidentified Gunner, Royal Artillery; and Private Gordon Lafayette Bryant 6969514, 117th Infantry Regiment, 30th Infantry Division, United States Army.
³ Crazy Horse Aviation Photography: https://crazyhorseap.be/mustangs/birth-of-a-legend/A-36.html
© 2025, Bryan R. Swopes