Following the abrupt dissolution of the Parliament of 1625, the Duke of Buckingham pressed ahead with plans for a naval expedition against Spain to rival the exploits of the Elizabethan heroes. The object of the expedition was to capture Spanish treasure ships returning from the Americas and to attack Spanish towns, commerce and shipping. By these means, Charles and Buckingham planned to weaken Spain's economy and to draw Spanish resources away from the Palatinate.
By October 1625, Buckingham had assembled a force of around 100 ships manned by 5,000 seamen and carrying 10,000 soldiers. He had also negotiated an alliance with the Dutch who agreed to send 15 warships with the expedition and to supply more to help guard the Channel while the main English fleet was away. Buckingham appointed Sir Edward Cecil commander of the expedition with Robert Devereux, Earl of Essex, as his Vice-Admiral. Cecil was an experienced soldier in the Dutch service, but he had little knowledge of naval warfare.
The expedition set sail on 6 October but the voyage was stormy. By the time the fleet arrived in Spanish waters it was clear that it was poorly supplied and that many ships were barely seaworthy. Delayed by storms, it arrived too late to threaten the West Indian treasure fleet.
Cecil decided to attack the city of Cádiz. He sailed into Cádiz Bay and succeeded in landing his troops and overrunning the fort that guarded the harbour. The city itself was strongly fortified. Spanish troops withdrew into the surrounding countryside to await reinforcements; the English pressed after them under a scorching sun. Someone suddenly realised that no provisions had been brought from the ships so foraging parties were ordered to look for supplies. They found that the whole area was a wine store for the Spanish West India fleets. Nothing could be done to prevent the English soldiers from pillaging the wine and soon most of the army was drunk. Cecil evacuated as many men as he could and put to sea. After a further three weeks' fruitless searching for treasure ships and battered by winter storms, the expedition limped back to England.
In order to protect Buckingham — who as Lord High Admiral should at least have ensured that the fleet was properly supplied — King Charles made no effective enquiry into what had gone wrong. Instead he turned his attention to the plight of the Huguenots of La Rochelle. Relations between England and France were deteriorating and Charles formed the conviction that he was honour-bound to liberate La Rochelle, thus erasing the ignominy of Cádiz.