 As a result of Cromwell's ambitious programme of naval expansion, at a time when the Dutch admiralty was selling off many of its own warships, the British came to possess a greater number of larger and more powerful purpose-built warships than did their rivals across the North Sea.However, the Dutch had many more cargo ships, together with lower freight rates, better financing and a wider range of manufactured goods to sell – although Dutch ships were blocked by the Spanish from operations in most of southern Europe, giving the English an advantage there.To protect its position in North America, in October 1651 the English Parliament passed the first of the Navigation Acts, which mandated that all goods imported into England must be carried by English ships or vessels from the exporting countries, thus excluding (mostly Dutch) middlemen.