To stop the Cuban revolution, Spain sent their best general, Valeriano Weyler, and his troops to force civilians into gaurded camps. The Cubans were desperate for help, and burned the American sugar cane in Cuba to get the attention of the US.
Mckinley keeps the peace
The Cubans wrote reports of the conditions in the camps: unsanitary, crowded, little food, and 200,000 citizens killed. They wrote this as yellow journalism to get American citizens wanting to fight for Cuba.
US list of demands
US Demands to Spain
The US moved a ship called the USS Maine into Havana's harbor to protect American citizens and sugar cane there. Later that year, the USS Maine exploded, and the blame was placed on Spain.
Treaty of Paris
Even after being disrespected in a letter written by a Spainard, President McKinley decided to keep America out of the war and not engage with Spain or Cuba.
The US sent demands to Spain to keep from starting war, including repayment for the USS Maine, no more camps in Cuba, and Cuban independence. Spain agreed to all but the last, so McKinley declared war.
The US and Spain signed the Treaty of Paris, promising Cuban independence and giving America control over the Philippeans, Guam, and Puerto Rico in exchange for $20 million for the Spanish.