At first Louis overrated this tendency of William’s diplomacy. He thought that if he was ready to give ample security for the safety of the United Provinces behind their barrier of the Netherlands, and for the security of English trade in the Mediterranean, he could procure Spain and the Indies for his grandson. [Sidenote: =Objects of Louis’s diplomacy.=] But he quickly found out his mistake, and he fell back upon two principles of action which determined his policy in the whole question from first to last as long as the negotiations lasted. The first was to guard against the revival of the power of the Austro-Spanish House through the succession question. The second was to neutralise the increase of the influence of the Habsburgs, by making the frontiers of France strong, not merely for defence but for offence. In pursuit of the first principle he opposed himself vigorously to the recognition of the archduke Charles as king of Spain, and when through the force of circumstances he was obliged to give way on that point, he did so only on condition that the connection between Spain and Austria through north Italy was cut by the granting of the Milanese to an independent prince, and rendered liable to annihilation by France through her acquisition of the Tuscan ports and Finale. Louis was not going to see the chain of the Austro-Spanish power, which it had cost Henry IV. and Richelieu so much to break, once more woven round her by the arts of diplomacy and the accidents of life. In pursuit of the second principle he took care, that if his grandson could not rule at Madrid, his own armies might have a way easily open to their advance thither by his acquisition of Guipuscoa; while he made his eastern frontier secure by the annexation of Lorraine, and strove hard to make it dangerous by his claim upon Luxemburg. [Sidenote: =Objects of William and Heinsius.=]