Prix Greffulhe
Souverain was a bay horse with a narrow white blaze and four white socks bred by his owner F. R. Schmitt. He was not an attractive colt, being described as a wall-eyed "ugly duckling" by a British observer. Souverain was sired by Maravedis, a horse which won the Prix Hocquart and Prix Greffulhe out of a mare named Jolie Reine. Apart from Souverain, Maravedis's most notable offspring were the Prix Royal Oak winner Samaritain and the Champion Hurdle winner Clair Soleil. As a descendant of the British broodmare Orris, Jolie Reine came from the same branch of Thoroughbred Family 23 as the 1949 Kentucky Derby winner Ponder. The colt was trained at Maisons-Laffitte by Henri Delavaud.