The book's main subjects are lashed together in its catamaran title. It analyses naval policy in the western European theatre of the Spanish Monarchy's wars, and focuses on the role of the Flanders armada in its evolution and execution. It illustrates a thesis which is now, if belatedly, recognised by most historians of the period – namely that Spain remained a major naval power for nearly a century after the defeat of the Invincible Armada, consistently seeking to defend its European hegemony by these means, which were as crucial to its policy as the deployment of land forces. That the army has recently been much more central to our perception of Spanish power is due in large measure to the early work of Geoffrey Parker. In fact, the latter's contributions have never ignored the maritime context of the Spanish System. Moreover, his study of The Army of Flanders and the Spanish Road (1972), one of the foundation volumes of the present series, has provided an exemplar of lucidly presented research which this book aspires (doubtless in vain) to complement.

Several cognate themes are encountered in the course of discussion. Two, in particular, may be seen as essential to the argument, if on a secondary plane. These are: privateering utilised as part of a mainstream naval strategy, and the central place of Dunkirk in this strategy. Insofar as it has any original aspects, my work seeks to contribute to this history of war and politics.