Arrival in Madrid
At the beginning of 1525, the French, lead by Frances I, re-conquered Milan, forcing the Imperial troops of Charles V to retreat to Pavia, waiting for reinforcements. On 25th February, to complete their success, the French laid siege to the city, but they were attacked from behind and, in the joint action of the Imperial armies descending from the north and exiting from the walls of Pavia, the were caught in the middle and heavily defeated. The King himself, Frances I, was captured and taken to Madrid.
Castiglione was informed of these events while he was travelling to Spain. On 11th March 1525 he arrived in Madrid; received solemnly at the Imperial court, he congratulated Charles V on the victory at Pavia. A short time later he presented an official document in which the Pope apologised for his recent alliance with the French.
In the course of 1525 and 1526, Castiglione sent long and detailed letters from Spain to the court in Rome, informing them about everything that was being discussed at the Imperial court. Baldassarre transmitted to the Pope opinions on what had happened and hypotheses about the future, in the light of the deliberations of Charles V that regarded all areas, both political and military, in the whole of Europe. Most of all, talking to Clemente VII, he insisted on defending his idea: the interests of the Church and the independence of Italy could be guaranteed only by a peace agreement, solid and lasting, between the Pope and the Emperor. He warned the Pope and his court of the dangers of an ambiguous and swaying policy, by means of which, in a short sighted double game, Rome offered its support to both the conflicting parties.
For Castiglione, the Spanish mission soon turned out to be full of dangers, particularly because, during his absence from Rome and without him knowing about it, the actions of the pro-French diplomats were gaining favour at court, surrounding the Pope and trying by every means to influence his decisions. Furthermore, Charles V proved to be a cold, calculating and astute interlocutor, whose real and secret movements seemed to Baldassarre always to be difficult to comprehend, developing, on both fronts, a sensation of growing and irrevocable isolation.
