Review not only Christopher Columbus, but also the Spanish-American War, and how the United States obtained its old interest in the Philippines, Puerto Rico and Guam.
Remember the Maine? This was the battleship that the US sent into Havana, Cuba to show the Spanish who was in charge when an insurrection was going on there.
But Spain sank it. The US rallied public opinion at home (governments are good at that) and declared war.: http//www.eyewitnesstohistory.com/spanishwar