The absence of a concerted joint effort by the Christian maritime powers allowed the corsairs of Barbary and Sallee to survive into the nineteenth century. This shameful failure of international cooperation had three main causes. In the first place, the great maritime nations were always suspicious of each other's intentions and were often reluctant to believe that a proposed attack on the corsairs was not a cover for some other more nefarious activity. Such suspicions were sometimes justified and so 'an expedition against the Barbary corsairs became the stock diplomatic formula for covering some ulterior and sinister design', as the historian Sir Julian Corbett put it in his study of England's early naval adventures in the Mediterranean. It also soon became apparent to the maritime powers that the Barbary regencies could be valuable allies in the numerous European wars of the seventeenth and eighteenth centuries, as long as peace could be negotiated with them. This made collusion in naval expeditions against Barbary almost impossible, since it became naval policy to exploit friendship with Algiers or the other regencies in order to gain an advantage over whichever of the other European powers was currently the enemy. The last reason for this failure was even more cynical and was noted as early as 1611 by the English consul in Syria. 'He remarked there were difficulties in the way of uniting sovereigns for the suppression of piracy, for some are not displeased that pirates exist and are glad to see certain markets harassed.' This observation made at a time when there seemed to be genuine hopes for cooperation became even truer in later years. The maritime powers, especially England and France, realised that if the corsairs could be persuaded by force and diplomacy to leave their shipping alone, these predators would then concentrate their attention on the shipping of weaker nations and so reduce the competition in trade. The French attitude towards Barbary was summed up in a memorandum of 1729. 'We are certain that it is not in our interest that all the Barbary corsairs be destroyed, since then we would be on a par with all the Italians and the peoples of the North Sea.' What France wanted was 'just enough corsairs to eliminate our rivals, but not too many'. Such sentiments were shared by the English, a nation who first condoned the piracy of its own subjects as it helped them force their way into the commerce and carrying trade of the Mediterranean and then exploited the piracy of the corsairs to sustain and increase their dominant position.SOURCE: The Pirate Wars, by Peter Earle (Thomas Dunne Books, 2003), pp. 72-74
This desirable if immoral position was to take a long time to achieve. The Barbary corsairs, especially those of Algiers, were formidable opponents in the 1620s and 1630s whose well-manned ships need feel little fear of the ships in the generally weak Christian navies of the day, since those they could not defeat in battle they could easily evade. 'It is almost incredible to relate in how short a time those ships out-sailed the whole fleet out of sight,' wrote the English Admiral Mansell after his failure to capture some corsair ships off Majorca on Christmas Day 1620. Algiers itself was virtually impregnable, a large, well-fortified city on what was normally a lee shore whose harbour was protected by a mole and a boom which could be drawn across if danger threatened. The other corsair cities were more vulnerable, but still offerred a formidable challenge to those who dared to attack them. And so, although many attacks were made on the ships and cities of the corsairs by the English, Dutch, French, Maltese and especially the Spaniards, not much progress was made in the first half of the seventeenth century. The Barbary corsairs, those 'pirates that have reduced themselves into a Government or State' as the jurist Charles Molloy neatly put it, remained a very great danger to the ships and coastlines of Christian Europe.
The situation was to change in the years after 1650 which saw a huge increase in the naval strength of England, Holland and, later, France and a growing commitment to the belief that one key function of such navies was to protect the nation's trade. These years also saw a change in the make-up of the European navies which had previously been dominated by large and very powerful ships. These remained, indeed became even more powerful, but they were now supported by much larger numbers of relatively small, fast vessels of shallow draught that had been originally designed to catch the privateers of the day but were of course also invaluable against the Muslim corsairs.