The last years of Jacobean rule coincided with the appearance of a number of Scottish soldiers at the three major Habsburg centres of power: Madrid, Brussels and the Imperial court (the last of which was still peripatetic but increasingly centred in Vienna). Recognising the geographical complexity involved in studying such individuals, the thesis seeks to contribute to the debates of historians of early modern Europe with respect to three issues: the problem of 'multiple kingdoms', the existence or otherwise of a seventeenth century 'general crisis', and the nature of political patronage at the regal court. The first chapter deals with the historical background. The remainder of the argument is divided into two sections, the first of which relates to the 1618-35 period. It covers the lives of men such as Colonel William Semple, his nephew, Hugh Semple S.J., and ambitious sojourners such as the seventh Earl of Argyll. The rise and decline of these individuals in influencing Spanish foreign policy is the subject of chapters two and three respectively. Chapter four introduces several Scottish 'military enterprisers' who rose to prominence in the service of the 'Austrian' branch of the dynasty after 1633. The second part of the thesis deals largely with the post-1635 life of one of this latter group, Walter Leslie. His significance will become obvious, yet has been ignored by previous historians. In fact, the court careers of all these individuals, elucidated here in detail for the first time, emphasise that the accession of James VI to the English throne by no means marks the end of the contribution of Scotland to continental European political and diplomatic history.