In Italy, therefore, lay the opportunity of France, and Savoy held the key of the position. The duchy of Savoy, which still extended as far as the Rhone, and disputed with the king of France for the rule over Provence and Dauphiné, had been gradually pushed by its more powerful neighbour more and more towards Italy. Its duke had quite lately established himself in his capital of Turin at the foot of the mountain, and his ambition was to become an Italian prince. But though Piedmont and not Savoy had become the centre of his power, the border land of Savoy and not the Italian land of Piedmont became necessarily the centre of his policy. Situated on the mountains between France and the Milanese, Savoy held the gates both of France and of Imperial Italy. Through her mountain passes could pour, when she gave the word, the troops of France into the fertile plains of Lombardy, or those of the Habsburgs into the valley of the Rhone. A position so decisive and so dangerous rendered a consistent policy impossible. Courted by both parties, her opportunity lay in playing off one against the other as long as possible, but her safety necessitated the choice of the stronger for her ally in the end. A misreading of the political barometer at a critical moment would mean nothing less than national extinction. From the time that the rivalry between France and the Austro-Spanish power began to develop itself in Italy, the dukes of Savoy had been compelled to follow this tortuous policy. During the Italian expeditions of Charles VIII. and Louis XII. they were on the side of victorious France, but in the war between Francis I. and Charles V. Savoy veered to the side of the Emperor. Punished for this by the occupation of his country by French troops for twenty-five years, the duke was reinstated in his dominions at the peace of Cateau-Cambrésis (1559), subject to the continued occupation by France of six fortresses, including Susa and Pinerolo, which commanded the gates of important passes through the Alps. In the troubles which afflicted France under the later Valois kings, Charles Emmanuel of Savoy succeeded in obtaining possession of Saluzzo; and although it was provided in the treaty of Vervins that he should restore it, the provision remained a dead letter. This gave Henry IV. the opportunity he desired of recalling Savoy to the French alliance. In 1600, after the death of Gabrielle d’Estrées, he had procured a divorce from his first wife Marguerite de Valois, and had strengthened his influence in Italy by his marriage with Marie de Médicis, the daughter of the grand-duke of Tuscany. [Sidenote: =Cession of Bresse and Bugey to France.=] In the same year he marched upon Savoy and quickly overran it, but in January 1601 agreed to a treaty with the young duke Charles Emmanuel, who had succeeded Emmanuel Philibert in 1580, by which Saluzzo was left in the hands of Savoy, but France obtained instead the two small duchies of Bresse and Bugey.