There was constant tension between Britain and the United States from 1840 to 1865. The Liberals, who dominated British government during this period, had no doubt why: American governments, pandering to the democratic mob, provoked crises with Britain for domestic electoral purposes. They did this by encouraging acts of aggression or provocation by American citizens, and by threatening and bullying the British government, in order to get their way on issues of contention. Furthermore, they succeeded, even though Britain's leaders usually thought either that right was clearly on the British side or was sufficiently ambiguous to justify greater concessions by the Americans than were finally secured. This policy of appeasing the United States was forced on Liberal governments because their middle-class constituency perceived a ‘special relationship’ between the two countries, based on blood, religion, liberal traditions, and trade. They would not contemplate the threat of war with the United States, and since no important British interest was involved, the British government usually gave way. When it did not, as during the Trent affair, the British interest was to prevent further crises.