Cromwell's foreign policy was active and aggressive; this gave Britain a new importance in Europe. Cromwell included religious considerations in his foreign policy. He passionately wanted to defend and spread Protestantism. There were also economic motives. He wished to expand the countries trade. But there was also security. He wanted to do anything to prevent foreign help to the exiled Stuarts, which might lead to dangers of a restoration. His concern for aid being sent to Charles 2nd throughout the 1650’s was reflected in his treaties with the Dutch in 1654 and with France in 1655, both of which agreed to clauses about the expulsion of the royalists from their territories. On of the Foreign policies successes was the victory against the Dutch. When Cromwell became Lord Protector, England was at war with the Dutch. Cromwell, who saw the Dutch, as Protestant brothers first and economic rivals second, disliked this inherited war. He made his attitude clear during the negotiations of 1653-54, which brought an end to the war. By this time he was the dominant power in Britain, and was prepared to sacrifice trading interests to acquire an Anglo-Dutch alliance against Catholic Spain. However the Dutch refused this agreement but signed the Treaty of Westminster in April 1654. Cromwell's hatred towards Catholic Spain led to an alliance with France against Spain, which led to the capture of Jamaica and Dunkirk. In 1655 a defensive alliance was signed between Britain and France, agreeing not to shelter Charles 2nd. However, in March 1657, this defensive alliance was converted into a military alliance against Spain. In October 1657, Mardyke was captured as well as Dunkirk in 1658. Cromwell had succeeded in securing Britain against royalist threat but also in acquiring an ally against Catholic Spain. Cromwell's dealings with the Baltic illustrate the difficulty in the 1650’s of trying to base foreign policy on purely religious concerns. Cromwell had respect for Swedish king Charlie x, and hoped that their two countries might form some kind of protestant union. This would allow Britain entrée directly into Baltic diplomacy. The growing importance, commercially of the Baltic powers with their navies made it imperative, that a major trading nation like Britain should have a direct say in such affairs. Neither the Protector of the Swedish king was happy with Dutch dominance in this area, which had created a disproportionate commercial advantage. Britain and Sweden in 1654 entered into a treaty to weaken the Dutch grip upon trade and to counterbalance an existing treaty between Holland and Denmark.
Accordingly Cromwell's foreign policy had failures. Initially Cromwell was deeply depressed by the failure to take Hispaniola but characteristically he came to terms with it by ascribing I to ‘the hand of God’. Cromwell found himself under fierce criticism over the war. One charge was religious zeal he had misunderstood the nature of ‘universal monarchy’, the main threat that came from France not Spain. Henry Vane spoke of France being ruled by ‘ the most tyrannical principles, and being intent on European domination. Others saw the danger coming from Sweden, which was under its powerful monarchy, Charles x, who had made substantial advances in the Baltic, an area of rapidly expanding commercial importance. One important voice was that of Slingsby Bethel, who believed that Sweden and France represented a joint threat: ‘These two countries are like to have divided the Western Empire between them’. Some critics complained that the war has disrupted their trade with Spain. They did not see it as necessary struggle since Spain was no longer a real power in Europe. They argued that she was a ‘lost nation’, meaning her greatness was a thing of the past. The question of cost was critical. Few were willing to pay the heavy taxes required by the war when the commercial outcome for themselves was loss rather than gain. The western design appeared to be pursuing unrealistic religious ends at the expense of serious commercial ones. Cromwell's ideologically motivated attitudes towards Spain had sacrificed British economic interests, and the French alliance of 1657, the capture of Dunkirk the following year and the glorious exploits of the navy could only conceal this fact. The Spanish war led to a loss of British trade to the Dutch, who benefited from their neutrality, and reduced the power of an already declining pain in Europe, and built up that of an emerging France, which would soon prove to be a serious political and economic rival of Britain.
Cromwell's foreign policy depended on the balance between three factors. The short term external greatness which it certainly brought to Britain; the longer term implications which it had for British interests by encouraging the rise of France and the Dutch at the expense of an already declining Spain; and the internal cost to the regime in merchant discontent and financial troubles. These financial troubles which were mainly caused by the expensive foreign policy of the 1650’s, this and the popular discontent with high taxation is perhaps one of the major reasons for the bring about of the restoration.
