during the bishops' wars the king attempted to blockade scotland, disrupting trade and the transport of returning troops from the continent. the king planned amphibious assaults from england on the east coast and from ireland to the west, but they failed to materialise. scottish privateers took english prizes and the covenanters planned to fit out dutch ships with scottish and dutch crews to join the naval war effort. after the covenanters allied with the english parliament they established two patrol squadrons for the atlantic and north sea coasts, known collectively as the "scotch guard". these patrols guarded against royalist attempts to move men, money and munitions and raids on scottish shipping, particularly from ships based in wexford and dunkirk. they consisted mainly of small english warships, controlled by the commissioners of the navy based in london, but it always relied heavily on scottish officers and revenues, and after 1646, the west coast squadron became much more a scottish force. the scottish navy was unable to withstand the english fleet that accompanied the army led by cromwell that conquered scotland in 1649–51. the scottish ships and crews were divided among the commonwealth fleet.