How long it lasted it is impossible to say, but it was brought to an abrupt end in the summer of 1669, when the Duc de Beaufort was given the command of the naval expedition which had for its object the relief of the Venetians who for twenty-four years had been besieged by the Turks in Crete. From this expedition he never returned, but before he sailed Louise took care to provide for her future by obtaining through his influence one of the posts of maid of honour to Madame which had just fallen vacant. This was the beginning of her fortune. The report that she accompanied Beaufort to Crete disguised as a page is a mere fabrication of her libeller. The Kéroual who accompanied the Duc de Beaufort to Crete was her younger brother, Sebastien, whom, no doubt, she now tried to provide for, as she did on a later occasion in England for her sister, Henriette. Sebastien, however, did not long enjoy the fruits of his sister's patronage; he died a few days after his return from Crete.
It was probably through this event that Louise became acquainted with the Comte de Sault, who on Beaufort's death appears to have taken Sebastien into his service, in which he was at the time of his death. This Comte de Sault was the eldest son of the Duc de Lesdiguières, and one of the best-known men at Court. He had won the chief prize a few years before in the famous jousts in front of the Tuileries, which gave their name to the Place du Carrousel. The Comte de Sault soon occupied more or less publicly the same place in the maid of honour's affections that had previously been held by the Duc de Beaufort. In fact, there was so little privacy about their relations that Madame de Sévigné and Louvois did not hesitate to put the worst construction on them, while several years later in England "a great peer taunted her insultingly with the recollection of this old scandal."
This affair was, however, decently conducted, as such things were in France, and Mademoiselle de Kéroual's social standing did not suffer. Perhaps she may have hoped to arrest the notice of the King himself, but if so she was disappointed. During the short time that she was in Madame's service the monarch's attention was too much absorbed by the beautiful Mademoiselle de la Vallière to be diverted by Mademoiselle de Kéroual. From all accounts Louis was scarcely aware of her existence till she was recommended to him as an agent likely to be of use in binding Charles II. hand and foot in the toils of French diplomacy.