He left France in 1557, but in 1558 he was again in that country, helping to arrange the preliminaries of the treaty of Cateau Cambrhsis.
In order to accomplish the first of these two preliminaries, the department established a Faculty of Agriculture at the Royal College of Science in Dublin, and offered a considerable number of scholarships the competition for which becomes increasingly keen.
He did not, however, as has been supposed, spend the best years of his manhood abroad, for he was certainly at home in 1571, when the preliminaries of his marriage were arranged at Merchiston; and in 1572 he married Elizabeth, daughter of Sir James Stirling of Keir.
He was ambassador at Berlin in 1866 at the time of the rupture between Prussia and Austria, and after the Seven Weeks' War was charged with the negotiation of the preliminaries of peace at Nikolsburg.
Victor Emmanuel regretfully signed the peace preliminaries, adding, however, pour ce qui me concerne (which meant that he made no undertaking with regard to central Italy), and Cavour resigned office.