The Restoration of the British monarchy in 1660 in the person of the bachelor Charles II produced a Europe-wide intrigue to provide him with a wife. In fact, almost from the beginning the Portuguese Princess Catharine of Braganza was the likely bride, and the international competition simply enabled Charles to increase his terms in the treaty of betrothal. From the first the English wanted the Portuguese North African port of Tangier as part of those terms.

Situated on the northwest corner of Africa, Tangier was a walled town and port, and had been Portuguese since 1471. It was not very strongly defended, and would probably have fallen to the local Moroccans in a few years if the Portuguese had kept it; nor was its port either commodious or particularly safe, being too shallow for larger ships. But its location, on the southern lip of the mouth of the Mediterranean, made it particularly attractive to fighting seamen in the light of experience gained in the previous decade. Edward Mountagu, now Earl of Sandwich, and Admiral Sir John Lawson, two eminent commanders who had been instrumental in bringing Charles across the North Sea to London, and both former officers of the republican navy, were enthusiastic advocates; unlike the king, they had actually seen the place, so their opinions carried some weight.

There were numerous other terms in the dowry in the betrothal treaty, including the transfer of Bombay, a reasonably large cash payment (never completely paid) and a military and naval alliance, intended to defend Portugal against Spanish attack, and which led to the presence of a considerable English military force in the country for the next ten years. But from the point of view of this book, it is Tangier which is the most interesting item.

The extent of the crisis which the prospect of the marriage produced is indicated by the fact that Lawson, in command of a fleet, having returned from Algiers, took up station in the Strait to deter any Dutch or Spanish interference in the transfer, and a defeat of the Portuguese in Tangier by the Moors precipitated a preliminary, precautionary occupation of the town by a force of English sailors to prevent a Moorish conquest.