Having done all that then appeared possible to secure the carrying trade of Asia, Africa, and America, the English Parliament now sought to obtain as much as was practicable of the import trade of Europe. Accordingly they further enacted that no goods of the growth, production, or manufacture of any country in Europe should be imported into Great Britain except in British ships, owned and navigated by British subjects, “_or in such ships as were the real property of the people of the country or place in which the goods were produced, or from which they could only be, or most usually were exported_.”[177] This stringent provision could only be aimed at the carrying trade of the Dutch, who had little or no produce of their own to export, and who for the reasons already mentioned had obtained a virtual monopoly of the carrying trade to many foreign markets. In such acts as these the long stifled feelings of animosity, animated by deep commercial jealousy which had been smouldering for years against the Dutch, at last found expression and relief. So strong indeed had these feelings become, that when the States despatched an embassy to England to solicit a revocation of the navigation laws just passed, it was found necessary to appoint a guard to protect the envoys from the popular resentment openly expressed against them. [Sidenote: War declared between Great Britain and Holland, April 1652.] England had now asserted the practical right to carry on her own over-sea trade in her own ships, and to obtain as much foreign trade as she could by her own industry and energy, and as this action was practically a defiance of the maritime supremacy of Holland, a struggle was evidently impending which could only be decided by an appeal to arms. But the Dutch amused the English Parliament with negotiations for a treaty, although in point of fact they had nothing to give as an equivalent for any concessions that England might make. In the meanwhile they got together one hundred and fifty vessels, and placing them under the command of Martin Tromp,[178] declared war against her in April 1652. As the desperate and sanguinary struggles which followed are matters of general history, it will be sufficient for our purpose if we recapitulate some only of the leading facts which show the effect of the war upon the merchant shipping of both countries.