Marsyas's dam was the highly successful broodmare Astronomie, whose other progeny included the undefeated Caracalla, Arbar, and Asmena.
In May of that year he raced outside France for the first time when he won the White Rose Stakes at Hurst Park and was part of an exceptionally strong[4] team of French stayers sent to Royal Ascot in June.
He bypassed the Ascot Gold Cup, in which his younger brother Caracalla defeated Chanteur, but won the longest race of the meeting, the Queen Alexandra Stakes over two and three-quarter miles.
[4] In October at Newmarket he moved down in distance and won the Lowther Stakes over one and a half miles beating the King's colt Rising Light.
[6] In his final season, Marsyas won the Prix du Cadran for the fourth time at the reopened Longchamp Racecourse beating Souverain by four lengths.
[7] Despite being the outstanding stayer in Europe in 1947, Marsyas was not included by the Timeform organisation in their annual Racehorses of 1947, as he did not compete in Britain or Ireland that season.