The aim of this thesis is to analyse Anglo-Dutch relations in this highly volatile period, as perceived and interpreted by both sides, and it also closes the gap between the notable theses of Grayson and Groenveld. On 23 August 1625 Charles I and the Dutch Republic concluded a partnership agreement for joint warfare at sea and a month later a treaty for war against Spain. In December 1625 England, Denmark and the Republic signed treaties to establish the nucleus of an alliance against the Austrian Habsburgs. Charles wanted an active role in continental politics. Also to compel Spain to support his aim to restore his exiled sister Elizabeth and husband Count Elector Frederick V to their Palatinate estates and Frederick to his Electoral dignities in the Empire. The Dutch wanted England as an active partner in their war with Spain. It was a partnership of convenience, with different objectives but with the intention that success would serve the interests of both. The perceptions of the partnership were also different. Charles saw it as a continuation from Dutch dependence on England in 1585 but in 1625 the Dutch saw themselves as strong enough on land and sea to withstand mighty Spain. However, their objective to have their sovereignty internationally acknowledged contrasted with Charles' wider foreign policy objectives. The successful diplomacy of the first nine months was followed by a premature Anglo-Dutch attack on Spain at Cadiz which met with defeat; it remained England's only military action against Spain. In 1627 England went to war with France in support of the Huguenots but had to withdraw. After the Cadiz expedition Charles expected the Dutch to join the Danes at war in the Empire and his own war against France, an atavistic notion that the Dutch in some vague sense were indebted to the English crown and would serve English interests.