From Imperial Spain: 1469-1716, by J. H. Elliott (Penguin, 2002), 2nd ed., Kindle Loc. 5954-97:
Seeing that his authority was gone and that law and order were everywhere collapsing, the unfortunate Count of Santa Coloma begged the town councillors of Barcelona to close the city gates against the casual labourers who always flocked into the city at the beginning of June to hire themselves out for harvesting. But the councillors were either unable or unwilling to agree; the harvesters made their usual entry; and on Corpus day, 7 June 1640, they inevitably became involved in a brawl. The brawl soon acquired the dimensions of a riot, and within a few hours the mob was hounding down the royal ministers and sacking their houses. The viceroy himself had moved to the dockyards for safety, but a group of rioters forced its way in, and Santa Coloma was caught and struck down as he attempted to escape from his pursuers along the rocky beach.
The murder of Santa Coloma left such authority as remained in Catalonia in the hands of the Diputació and of the city councillors and aristocracy of Barcelona. Although they managed to shepherd the rebels out of Barcelona itself, it was impossible to maintain control over a movement which was spreading through the Principality, wreaking vengeance on all those of whom the rebels disapproved. Stunned as he was by the viceroy’s murder, Olivares still seems to have hoped that the rebellion could be checked without recourse to arms, but the new viceroy, the Catalan Duke of Cardona, died on 22 July without being able to halt the drift to anarchy. Almost at the same moment the rebels gained control of the vital port of Tortosa. The loss of Tortosa made it finally clear that troops would have to be sent into Catalonia, in spite of the obvious risk of war in a province bordering on France; and Olivares pressed ahead with the formation of an army for use against the rebels.
The Conde Duque believed that the Catalans were still too loyal to call on the French for help, but he underestimated the determination and vigour of Claris, and the hatred of his Government and of Castile which his policies had inspired in every class of Catalan society. Some time before, Claris had already made tentative overtures to the French, and Richelieu, who had shown himself well aware of the possibilities of causing trouble both in Catalonia and Portugal, declared himself ready to offer help. During the autumn of 1640 Claris and Olivares stood face to face, Claris hoping to avoid the necessity of committing the Principality to an open break with Madrid, and Olivares equally hoping to avoid the necessity of using an army against the Catalans. ‘In the midst of all our troubles,’ wrote the Conde Duque to the Cardenal Infante in October, ‘the Catalan is the worst we have ever had, and my heart admits of no consolation that we are entering an action in which, if our army kills, it kills a vassal of His Majesty, and if they kill, they kill a vassal and a soldier…. Without reason or occasion they have thrown themselves into as complete a rebellion as Holland….’
But worse was to come. The revolt of the Catalans was bound to have its repercussions in Portugal, where there was a growing determination to cut the country’s links with Castile. Uneasily aware that he could never be sure of Portugal as long as the Duke of Braganza and the higher Portuguese nobility remained at home, Olivares had ingeniously thought to kill two birds with one stone by ordering the Portuguese nobility to turn out with the army that was to be sent into Catalonia. This order meant that, if Portugal was ever to break free from Castile, it must act quickly before Braganza was out of the country. Plans for a revolution were laid in the autumn of 1640, probably with the connivance of Richelieu, who is believed to have sent funds to the conspirators in Lisbon. On 1 December, while the royal army under the command of the Marquis of los Vélez was gingerly advancing into Catalonia, the Portuguese conspirators put their plan into action. The guards at the royal palace in Lisbon were overwhelmed, Miguel de Vasconcellos – Olivares’s confidant and principal agent in the government of Portugal – was assassinated, and Princess Margaret was escorted to the frontier. Since there were virtually no Castilian troops in Portugal, there was nothing to prevent the rebels from taking over the country, and proclaiming the Duke of Braganza king as John IV.
The news of the Portuguese Revolution, which took a week to reach Madrid, forced Olivares and his colleagues to undertake an urgent reappraisal of their policies. Simultaneous revolts in the east and west of the Spanish peninsula threatened the Monarchy with total disaster. Peace was essential: peace with the Dutch, peace with the Catalans. But although the Conde Duque now offered favourable terms to the Catalans, and the upper classes in Catalonia seemed predisposed to accept them as the army of los Vélez moved closer and closer to Barcelona, the populace was in no mood for surrender. It rioted in Barcelona on 24 December, hunting down ‘traitors’ with a savagery surpassing that of Corpus; and Claris, faced on one side with the fury of the mob, and on the other with the advancing Castilian army, took the only course open to him. On 16 January 1641 he announced that Catalonia had become an independent republic under French protection. Then on 23 January, finding that the French were not satisfied with this, he withdrew his plans for a republican system of government, and formally declared the allegiance of Catalonia to the King of France, ‘as in the time of Charlemagne, with a contract to observe our constitutions’. The French were now prepared to give the Catalans full military support; the French agent, Duplessis Besançon, hastily organized the defence of Barcelona, and on 26 January a combined French and Catalan force met the army of los Vélez on the hill of Montjuich outside the walls of Barcelona, Los Vélez unaccountably gave the order to retreat, and the last chance of bringing the revolt of the Catalans to a speedy end was lost.