On February 15, 1898, the battleship USS Maine  exploded in Havana harbor. Cuba was in the throes of a rebellion against its Spanish overlords, and the US was concerned about its safety, as Cuba is only 90-some miles from the US border. The Maine was dispatched to Cuba to demonstrate American force and presence.

Meanwhile, Americans were itching for a fight. There are whole libraries of materials  about why this was so, but you can just start here . Mostly, historians attribute that impulse to "expansionism," the desire by Americans to get a piece of colonial action and get out in the world. Also, the world Americans knew in the 19th century was disappearing: "Local" was losing significance as the center of people's experiences, and the larger world was encroaching on daily life. Trains took people to the edge of the world, and industrial growth changed how and what they consumed. Newspapers had become a quick medium of messaging, as well as the primary medium. Like TV today, news broke fast and loud and was available almost immediately. And like TV today, the news was often suspect in its source.

On the night of February 15th, there was an explosion on the Maine, and she sank. The US was outraged, blamed Spain because the ship was in their harbor, and went to war . An era of imperial adventures began with the Maine incident. The whole thing was one big blow-up, so to speak, and got everyone into a lather. Newspapers sold copies, politicians made careers, restless boys were issued guns and given uniforms, and the nation acquired territory.

Mostly, Americans got their ya-yas out .