The term "War Hawk" is of late eighteenth-century origin and was used to describe anyone who favored a belligerent foreign policy. It was first consistently applied to a group of politicians in the Twelfth Congress led by Henry Clay, the Speaker of the House.

The War Hawks wanted war against Britain for a number of reasons. First, maritime hostilities between the two nations had been escalating for several years. The British embargo against its partners trading with France during the Napoleonic Wars had led already to increased tension. Then there was controversy over whether deserters from the British military could take United States citizenship. This led to events such as the Chesapeake Incident, in which the crew of a British ship attacked and boarded the USS Chesapeake to look for deserters, causing widespread outrage among Americans.

Another cause for conflict was the British policy of supporting and arming Native American tribes which attacked United States settlers in the Northwest Territory. The British regarded Tecumseh, the Shawnee leader, as a valuable ally whose territory provided a buffer between the American settlers and British colonies in Canada. The aim was to create a permanent Native American barrier state, a policy that the British continued to pursue even after the beginning of the War in 1812. Politicians from the West were, therefore, strongly represented among the War Hawks.