<P> Maass argued in 2015 that the expansionist theme is a myth that goes against the "relative consensus among experts that the primary U.S. objective was the repeal of British maritime restrictions . He argues that consensus among scholars is that The United States went to war "because six years of economic sanctions had failed to bring Britain to the negotiating table, and threatening the Royal Navy's Canadian supply base was their last hope ." However, he also notes that many historians continue to publish in support of expansionism as a cause, and that even those opposed to the idea continue to include caveats regarding "possible expansionism underlying US motives". Maass agrees that theoretically expansionism might have tempted Americans, but finds that "leaders feared the domestic political consequences of doing so . Notably, what limited expansionism there was focused on sparsely populated western lands rather than the more populous eastern settlements (of Canada)." </P> <P> The long wars between Britain and France (1793--1815) led to repeated complaints by the U.S. that both powers violated America's right as a neutral to trade with both sides . Furthermore, Americans complained loudly that British agents in Canada were supplying munitions to hostile Native American tribes living in United States territory . </P> <P> Starting in the mid-1790s the Royal Navy, short of manpower, began boarding American merchant ships in order to seize American and British sailors from American vessels . Although this policy of impressment was supposed to reclaim only British subjects, the law of Britain and most countries defined nationality by birth whereas the United States allowed individuals who had been resident in America for some time to adopt American citizenship . There were, therefore, large numbers of individuals who were British by British law but American by American law . The confusion was compounded by the refusal of Jefferson and Madison to issue any official citizenship documents: their position was that all persons serving on American ships were to be regarded as US citizens and that no further evidence was required . This stance was motivated by the advice of Albert Gallatin, who had calculated that half of American deep - sea merchant seamen - 9,000 men - were British subjects . Allowing the Royal Navy to reclaim these men would destroy both the US economy and the vital customs revenue of the government . Any sort of accommodation would jeopardize these men, and so concords such as the proposed Monroe - Pinkney Treaty (1806) between the U.S. and Britain were rejected by Jefferson . </P> <P> To fill the need for some sort of identification, US consuls provided unofficial papers . However, these relied on unverifiable declarations by the individual concerned for evidence of citizenship, and the large fees paid for the documents made them a lucrative sideline . In turn, British officers - short of personnel and convinced, not entirely unreasonably, that the US flag covered a large number of British deserters - tended to treat such papers with scorn . Between 1806 and 1812 about 6,000 seamen were impressed and taken against their will into the Royal Navy of which 3,800 were subsequently released . </P>

What were two major causes of the war of 1812