The War of 1812 and the Mexican-American War are two wars that physically appear two opposites. The War of 1812 involves plenty of naval battles and a few major land battles, while the Mexican-American War involves numerous land battles and few, if any, naval battles. However there are numerous similarities.
The War of 1812, The US saw Great Britain as a major problem because of their definition of "contraband" and the impressment of American sailors into the British Navy. And around this time the "warhawks" are elected to the House of Representatives. They wanted war because the British were supplying the Indian with guns and ammunition and encouraging Indian trouble.
William Henry Harrison is sent west to face off against Indian warchief, Tecumseh at the Battle of Tippecanoe. After the fight the Americans find British weapons with the fallen Indians. The Warhawks are convinced that we can capture Canada, which they wanted for its fish, furs, land, and lumber.
Warhawk Henry Clay is elected Speaker of the House, and appoints warhawks to the house committee on Foreign Relations.
The Mexican American War was partly began by the president and Mexico together. Polk wins the Election of 1944, and Tyler annexes Texas on March 2, 1845.
We aren't sure on the southern boundary of Texas. Mexico claims it's the Nueces River while the US say it's the Rio Grande. On top of this the US wants a war with Mexico with the hope of forcing Mexico to hand over California. Polk sends an army commanded by General Zachary Taylor into the disputed territory.
So both of these wars are started with the expansion of the United States' boarders as a main idea. The Warhawks want Canada and Polk wants California, both for reasons of commerce.
Mexico sends its own army and...