In the same month King Ferdinand wrote a most affectionate letter to Margaret evidently in the hopes of winning her consent to his wishes by flattering speeches. The letter is addressed to his 'beloved daughter,' and begins by thanking her for all the great services she has rendered to himself as well as to 'his brothers, the emperor and the King of England, and to his son, the Prince (Charles).' 'She is,' he says, 'the most important person in Christendom, since she acts as mediator in almost all the negotiations between the princes of Christendom.' In another letter to Lanuza a few days later, Ferdinand is still anxious lest Margaret should oppose the truce with France, and observes that 'Madame Margaret is the person on whom, more than any one else on earth, peace or war depends, and beseeches that she may use her influence in favour of peace.' King Ferdinand tells Lanuza in confidence that he believes Margaret wishes to marry the French king herself, and that if this is the case, Ferdinand would not oppose it; but the King of France is anxious to marry again because he hopes for a son and heir, and he does not wish to marry Margaret because he fears that she would not bear him children....[46] [46] _Calendar of Spanish State Papers_, vol. ii. Whilst these negotiations were under discussion, Henry VIII. was contemplating marrying his sister Mary to Louis XII., in order to prevent the French king's marriage with Eleanor of Austria. It was now in the King of England's interest to be on good terms with France, as he was deserted by those who had formerly sided with him against her. Full powers for Princess Mary's marriage with Louis XII. were sent to France on the 29th of July. The next day Mary solemnly renounced the promises made in her name with reference to her marriage with the Archduke Charles, and on the 7th of August the marriage contract with Louis was signed in London by the ambassadors, without Margaret having any suspicion of the truth. When at last she heard rumours of the Anglo-French marriage, she did not believe them, and even ordered Jacques de Thienne, Lord of Castres, to tell the King of England that she had never believed the report to be true. De Castres only started on his mission in the middle of August, and the marriage treaty had been signed since the 7th of the same month, and Mary had married the prisoner Duke of Longueville[47] by proxy at Greenwich on the 13th. [47] The Duke of Longueville had been a prisoner in England since the battle of Guinegate. This public ceremony at last convinced Margaret of the unwelcome fact that her nephew had been thrown over. She bitterly complained of King Henry's want of good faith, and threatened to publish the promise he had given in writing to marry his sister to the Archduke Charles.