Cromwell understood warfare on the sea, though his own magnificent victories had been won on land. He also understood the three things Britain needed then to make and keep her great: first, that she should be strong enough to make foreigners respect her; secondly, that her oversea trade should be protected by a strong navy; and thirdly, that she should begin to found a British Empire overseas, as foreigners always tried to shut the British out of their own oversea dominions.
In 1654 a fleet and army were sent against the Spanish West Indies; for, though there was no war with Spain in Europe, there never was any peace with Spaniards overseas. Cromwell's orders, like those of Pitt a hundred years later, were perfect models of what such orders ought to be. He told the admiral and general exactly what the country wanted them to do, gave them the means of doing it, and then left them free to do it in whatever way seemed best on the spot. But the admiral and general did not agree. King's men and Cromwell's men had to be mixed together, as enough good Cromwellians could not be spared so far away from home. The leaders tried to stand well with both sides by writing to the King; and every other trouble was made ten times worse by this divided loyalty. Jamaica was taken. But the rest was all disgraceful failure.
A very different force sailed out the same year under glorious Blake, who soon let Spaniards, Italians, and Barbary pirates know that he would stand no nonsense if they interfered with British vessels in the Mediterranean. The Italian princes were brought to book, as the Spaniards had just been brought to book at Malaga. Then Blake swooped down on the Moorish pirates' nest at Tunis, sinking every vessel, silencing the forts, and forcing the pirates to let their Christian slaves go free. After this the pirates of Algiers quickly came to terms without waiting to be beaten first.
Meanwhile the frightened Spaniards had stopped the treasure fleet of 1655. But next year they were so short of money that they had to risk it; though now there was open war in Europe as well as in New Spain. Running for Cadiz, the first fleet of treasure ships fell into British hands after very little fighting; and Londoners had the satisfaction of cheering the thirty huge wagon-loads of gold and silver booty on its way to safekeeping in the Tower.