In August, 1578, only a few weeks before the death of Don Juan relieved him from his worst dilemma in Catholic Flanders, his rash young nephew, King Sebastian of Portugal, was killed in battle in Morocco. His heir was the old childless Cardinal Don Henrique, and amongst the many subsequent claimants Philip was the strongest. With the added power and great wealth of Portugal, the King of Spain might conquer heresy yet by force, and defy both England and France if needs be, for, with the harbours of Spain, Portugal, and the Islands closed to them, French and English ships would be unable to sail far from their own shores. The danger at once drew Catharine and Elizabeth together, but they could do nothing effectual yet, and all Philip’s plans were laid carefully to seize the throne of Portugal when the aged king should die. It was necessary, amongst other things, for him to provide that both Elizabeth and Catharine, when that event happened, should have their hands full at home, and the effect of his manœuvres is noticeable almost immediately. Mendoza had been instructed to use the greatest caution in all approaches to him on behalf of the imprisoned Mary Stuart; but in January, 1579, Zayas wrote to him, saying that negotiations had been opened by Beton, Archbishop of Glasgow, Mary’s ambassador in Paris, and the Spanish ambassador there. “If,” he said, “Philip would provide enough money to raise four thousand troops, great things might be done for her and for the Catholic religion. His Majesty is very well disposed towards it; but nothing, as yet, has been decided, because, in good truth, the matter could only be undertaken on very safe grounds, and with the assurance that the effect would be produced, as otherwise it would be _oleum et operam perdere_. Send us your opinion on it.”[228] The French intrigues in Scotland at this period (1579) had somewhat aroused the apprehensions both of Philip and Elizabeth, for Guise had sent young Lennox d’Aubigny, the Franco-Scot Stuart, to woo his cousin James, and he had succeeded beyond the wildest expectations. Philip was willing enough to foster Guise’s ambitions to the extent of setting him against Catharine and the Huguenots; but any attempt at Guisan interference in Great Britain without his direction always alarmed him, so Mendoza lost no opportunity of whispering to Elizabeth distrust of French aims in Scotland.