War with Spain
The sinking of the Maine was the final act pushing the United States to declare war on Spain. This war was very one sided, with the United States Navy achieving overwhelming naval victories both in the Philippines and in Cuba. US forces captured the Philippines, Cuba and Puerto Rico..
Cuban revolutionaries began fighting for independence from Spain in1895. Their fight received a great deal of sympathy in the United States. Cuba was close to the US and the United States had for almost 100 years worked to limit European influence thus it was clear where American sympathy lay. In addition, this was the period of time that the term yellow journalism was born. Penny newspapers promoting a story, and many gave tremendous coverage to the “atrocities” committed by the Spanish against the rebels.
Thus relations between the US and the Spanish government were tense. The US Battleship Maine made a routine visit to Cuba, and then on February 15, 1898, the ship blew up in Havana Harbor, the cause of the explosion has never been definitively explained, but at the time everyone believed it was the Spanish who were responsible.
From that moment it was clear that war was inevitable. The Congress passed a declaration of war against Spain on April 25th.
The outcome of the war was never really in doubt. The US was a growing power, whose navy had been growing rapidly, Spain was declining European power. The US navy quickly defeated the Spanish navy both in the Philippines and in Cuba. This allowed the invasion of both places to proceed. The Spanish troops were quickly defeated on land as well. When the war ended the US was occupying the Philippines, Cuba and Puerto Rico.