One cause of the War of 1812 was settlers who were pushing westward into Native American lands. This led to conflict with Native American tribes, who were often allied with the British. The British were also accused of supporting Native American resistance to American expansion, which further strained relations between the two countries. Additionally, there were ongoing disputes over trade and maritime rights, with the British imposing trade restrictions on the United States and seizing American ships. All of these factors contributed to the outbreak of war in 1812.