Polk's tough talk and negotiations with the British saw him securing the North-West regions for America. That's a very large piece of land. To the South, he tried to secure it from the Mexicans. This time his tough talk did not work. So he planned to wage war by goading and badgering the Mexicans, spoiling for a fight. Then when the Mexicans finally fired shots at the Americans, Polk took this opportunity to go to war.
1:56 min - But Congress was not willing to support a war. Polk then went to the American people for support. Using the patriotism platform as the motivator, he got the American people to overwhelmingly back him on his cause for war against others. Doesn't that sound very familiar today, where the President of the US will stoke emotive words on patriotism to invade lands of others on the pretext of waging "war on terror"?
http://wherebearsroamfree.blogspot.sg/2013/07/american-liberty-stealing-lands-of.html
