The British government failed to take into account the strength of the American merchant marine and support from European countries, which allowed the colonies to import munitions and continue trading with relative impunity. While well aware of this, the North administration delayed placing the Royal Navy on a war footing for cost reasons; this prevented the institution of an effective blockade and restricted them to ineffectual diplomatic protests. Traditional British policy was to employ European land-based allies to divert the opposition, a role filled by Prussia in the Seven Years War; in 1778, they were diplomatically isolated and faced war on multiple fronts.