Souverain

Souverain ran only once as a two-year-old, winning a race over 1800 metres (nine furlongs).[5]

Souverain recorded his first important success when he won the three-year-old version of the Prix Jean Prat over 2000 metres at Longchamp Racecourse in April. A month later he finished third to Adrar in the 2400 metre Prix Hocquart. The colt returned to Longchamp in July for the 3000 metre Grand Prix de Paris for which he started a 53.5/1 outsider. Ridden by Marcel Lollierou he won by a short head from the Prix du Jockey Club winner Prince Chevalier.[6] The result was decided by a photo finish,[7] then a relatively new technology which was not introduced to Britain until 1947. In October, Souverain recorded another important success when he defeated Prince Chevalier in "storming fashion"[2] in the Prix Royal Oak, the French equivalent of Britain's St Leger Stakes.

On his final start of the season he was sent to England for the inaugural King George VI Stakes over two miles at Ascot where he was matched against The Derby winner Airborne and the Irish Derby winner Bright News. The race carried prize money of £5,000 and was billed as the "international championship" for three-year-olds.[8] Ridden as usual by Lollierou, Souverain "shot clear" of the field in the straight and won easily by five lengths from Bright News, with Airborne, the favourite, in third.[9] The success of Souverain reportedly "shattered" the belief of British breeders in the superiority of their staying horses. Among the theories advanced to explain his win was the supposedly unlimited supply of milk and German oats provided to French horses at the end of the Second World War.[5] Lord Brabazon, writing in Nature blamed bad tactics by British jockeys who tended to restrain their mounts before accelerating in the closing stages and was supported by the physiologist Archibald Hill who argued that horses performed better when they ran at a uniform speed.[10] French experts however, pointed to the tendency of British breeders to undervalue stamina in pedigrees and place undue emphasis on sprinting and two-year-old races.[5]

By the end of the season, Souverain was regarded as Europe's Champion three-year-old and valued by his owners at the "unheard of" sum of £160,000.[11] Late in 1946, the American magazine Time proposed an international championship race in which Souverain and the Australian champion Bernborough would be matched against leading American runner Stymie, but the event never came to fruition.[12]

As a four-year-old, Souverain won the older horses' version of the Prix Jean Prat (the race now called the Prix Vicomtesse Vigier) at Longchamp in May.[4] Later that month he ran in the 4000 metre Prix du Cadran but was decisively beaten by the seven-year-old Marsyas who was winning the race for the fourth time.[13] In June, he was sent to race in Britain for the second time, when he contested the Gold Cup over two and a half miles at Royal Ascot. He started at odds of 6/4 and won by four lengths from the other French challenger Chanteur, who had been made odds-on favourite. The prize money of £11,316 made the race the most valuable ever run in Britain up to that time.[14]

Souverain returned to France in August and recorded his last important success when he won the Prix Kergorlay at Deauville Racecourse.[4] In autumn 1947, Souverain contracted a respiratory infection and was retired from racing.[15]