that the British were arming and inciting the Native American Indians to attack American settlers.

Finally, some argued that war was necessary to maintain American sovereignty and to restore national honor, both of which had been attacked by the British actions on the high seas and on the American frontier.

The previous thoughts were well articulated.  I would like to add that the idea of arming Native Americans really pushed the buttons of the Americans.  To them, it seemed like the Revolutionary War all over again.  The Americans had done an effective job of relegating out the Native Americans from political and social forms of power.  The very idea that the British would arm them and encourage them again caused a great deal of zeal and nationalism amongst many Americans, who saw this as another opportunity to defend honor. Leaders like Henry Clay used their political power as ways to ensure that nationalistic policies were advanced.  At the same time, Native American resistance to White Expansion began to become increasingly pronounced.  Leaders like Tecumseh and the Prophet advocated that the emphasis on Native American traditions and ways of life were threatened with White expansion.

The War of 1812 happened largely because the English had not really accepted the idea that the US was an independent country.  The things that England did led Americans to want to go to war. 

After the Revolutionary War, the United States became an independent country.  However, the British did not seem completely willing to accept this.  At the very least, they did not have much respect for American sovereignty and did not fear American retaliation for anything they did.

Because of this, the British did three main things that annoyed the Americans and helped lead to the war.  First, they kept forts on American territory.  These forts were in the area that was called the “Northwest” at that time.  Second, the British used these forts to arm Indians and to provoke them into attacking American settlers.  Finally, the British were not respecting the rights of American ships and sailors.  They would stop American ships and would force some of the sailors on those ships to become part of the British navy.  This was a practice known as impressment.

These were the main factors that caused the war to begin.

The War of 1812 took place for three reasons. First, American trade on the high seas was hindered by the British and their powerful navy. Second, the British navy impressed sailors into their service. And finally, the Americans blamed the British for continual Native American uprisings on the American frontier.

Britain and France were engaged in a very long war between 1793 and 1814—except for one year of peace in 1802. The French armies dominated Europe, but British ships were supreme at sea. Neither side could achieve a decisive victory. The two nations tried to starve each other by blocking their rival's trade with other nations. The US managed to trade with both during the first decade of hostilities. After 1805, however, America's lucrative foreign trade was endangered. Because the British fleet was stronger than the French one, London did more damage to American trade than the French did.

The British also earned American condemnation for their practice of impressment. The British boarded American ships and impressed some sailors into the Royal Navy. The British claimed that these sailors had deserted and that they had a right to seize them.

There was also a group of "war hawks" in the United States. These leaders came from the West and the South, and they blamed the British for Indian uprisings on the frontier. There was an important battle between the Americans and Indians at Tippecanoe in 1811. The "war hawks" played a key role in bringing on the War of 1812.

The War of 1812 (1812–1815) ended in a draw. Napoleon was defeated and exiled in 1815, so trade on the high seas ceased to be an issue. Tecumseh's death in battle in 1813 ended the Indian threat to American frontiersmen.

The War of 1812 had several causes:

• Great Britain's War with France. Despite brief peaceful interludes, Britain and France had been at war for hundreds of years. Now that the United States was independent, both nations wanted to trade with it, and they also wanted to stop the United States from trading the other nation supplies. The United States wanted to trade freely, so they told Britain and France they would stop trading with the opposing power if they ceased to restrict American trade. France complied with this request, so the United States stopped trading with Britain. As you might imagine, this angered the British.
• Impressment. One of Britain's trade restrictions required neutral nations (such as the United States) trading with France to apply for a license from Great Britain. The British navy stopped any vessel which did not have a license, confiscated its cargo, and forced the sailors to work on the British naval ships (this was called impressment). Clearly, this infuriated the United States.
• Lingering resentment from the American Revolution. Many British people believed that Britain should have stopped America from winning independence, so they hoped that they could re-conquer their former colonies. Many in the United States, on the other hand, regretted that they had been unable to conquer Canada during the Revolution. They saw another war as an opportunity to expand their territory into the North.

During the Franco-British Wars, American merchants had traded with both sides, even though the U.S. was nominally neutral. Both sides took steps to prevent American trade with the other. However, the primary cause of the American declaration of War was the impressment of American soldiers into service on British ships. Service in the British navy was brutal, so much so that British sailors were not allowed to leave ship when in port, even in the ship's home port, as it was feared by the commanders that the sailors would not return. Some did escape, of course, and Britain began a policy of stopping American ships to search for deserters. Not only was stopping the ships offensive; there was evidence that some innocent Americans were taken from the American ship and forced into service on the British ship. This was the primary reason for the declaration of war. An underlying cause was the desire of the War Hawks in Congress, including John C. Calhoun, and Henry Clay, to make Canada a part of the U.S. Although they argued that the war was to protect national honor, others saw it differently. Sen John Randolph commented:

We have heard but one word—like the whippoorwill, but one eternal monotonous tone: "Canada! Canada! Canada!

Diplomatically, the war accomplished little or nothing for the U.S. At the end of the war, the British had burned Washington and there was only one major American victory, the Battle of New Orleans which was fought two weeks after the signing of the Treaty of Ghent. The Treaty, which ended the war, re-established the status quo ante bellum. Impressment, the stated casus belli, was not even mentioned. Domestically, the war engendered intense patriotism and nationalism, and led to the "Era of Good Feelings." One should also note that it was during the war of 1812 that Francis Scott Key composed The Star Spangled Banner.

The War of 1812 is generally taught as "The American Revolution II", because it was largely an extension of the first American Revolution.

Britain and France had long been ignoring American neutrality -- they impressed sailors into service, seized ships and merchant goods, and continued fighting their wars on American soil. The two nations had a long-standing feud born of a medieval conquest and the rights of feudal lords: a fight America wanted nothing to do with!

Britain was engaged in a battle with Napoleon and America wanted to continue to trade -- needed, really, because as a fledgling nation we needed to build an economy. Britain blockaded us from trading, then France did the same, and the War Hawks in Congress (pro-war) pushed their agenda through. Eventually, it was decided that the US would declare war to assert itself and to protect itself economically. It was a lackluster war with little change at the end, but we did thereafter declare ourselves protectors of the Americas and engaged in a policy of neutrality.