The circumstances in which this startling death occurred have aroused the attention of historians. Madame had returned from England, where she had succeeded in getting the Treaty of Dover signed on June 1, 1670, by the ministers of her brother Charles II--the treaty assuring Louis XIV of the alliance of England against Holland, and permitting him to conquer Flanders and Franche-Comté for France. Madame remained at Dover from May 24 to June 12; she then re-embarked for France, happy in the successful result of her mission; and she arrived at Saint-Germain on the 18th. 'At the age of twenty-six,' says Madame de la Fayette, 'she saw herself the link between the two greatest kings of the century; she had in her hands a treaty on which depended the fate of a part of Europe; the pleasure and the importance given by affairs of moment being joined in her with the attractions bestowed by youth and beauty; there was a grace and a sweetness enveloping her whole person that won for her a kind of homage, which must have been the more pleasant in that it was rendered rather to her personality than to her rank.' Need anything be said of the manners of Monsieur? 'The miracle of firing the heart of this prince,' says Madame de la Fayette, 'was reserved for no woman in the world.' And yet his heart was wonderfully tender! Madame had definitively secured the exile of the Chevalier de Lorraine, the infamous friend of her husband. Madame died suddenly at St. Cloud, a prey to the most cruel anguish, on the night of the 29th of June 1670, about three o'clock in the morning. Rumours of poison were instantly set afloat, which were not long in gaining strength and currency. They formed the general opinion at Court, in Paris, in the whole of France, in England, Holland, and Spain, where Madame's daughter became queen. Charles II refused to receive the letter in which the Duke of Orleans informed him of his sister's death. 'The Duke of Buckingham, the English ambassador,' wrote Colbert de Croissy, 'is in transports of rage.' The people of London were hardly restrained from violent outbursts against the Frenchmen residing there. The streets rang with the cry of 'Down with the French!' The French embassy had to be protected. Monsieur's second wife, Madame Palatine, was always convinced that Madame had died of poison, and everything tends to show that Louis XIV, at all events in the first moments, shared these suspicions.