In 1854, he toured America with Giulia Grisi, earning both money and adulation during their trans-Atlantic jaunt. Mario could not marry Grisi because she was already married to Gérard de Melcy. Although Grisi and de Melcy were separated, divorce was not permitted by the Catholic Church in Italy neither in France, eventually, she married Mario in London England. Before meeting Mario, Grisi had had a son by Lord Frederick Stewart, a nephew of the famous Robert Stewart, Viscount Castlereagh. The child was acknowledged by Castlereagh with the name Frederick Ormsby. He was later recognized as an adoptive son through his mother's marriage to Mario; he was known as Frederick Ormsby de Candia, socially styled as Fredo de Candia.