At 9:40pm on February 15, 1898, the battleship U.S.S. Maine exploded in Havana Harbor, killing 268 men and shocking the American populace.
The reasons for war were many, but there were two immediate ones. America’s support of the ongoing struggle by Cubans and Filipinos against Spanish rule, and the mysterious explosion of the battleship U.S.S Maine in Havana Harbor.
The United States went to war against Spain in 1898 because they wanted to further their annexations.



The factors that led to U.S. victory was having the advantages of a demoralized foe and knowledgeable Cuban allies.
In 1898 the United States declared war on Spain following sinking of the battleships Maine in Havana Harbor.
The war ended with the signing of the Treaty of Paris on December 10, 1898.
The Jacobins, rebels who had taken over France, began declaring war on different monarchies, and because the U.S. were allies with France, they expected help.
Not wanting to get involved, the U.S. declared neutrality. In 1794 the Battle of Fallen Timbers was fought.
Ostensibly on a friendly visit, the Maine had been sent to Cuba to protect the interests of Americans there after riots broke out in Havana in January. An official U.S U.S. Naval Court of Inquiry reported on March 28 that the ship, one of the first American battleships and built at a cost of more than two million dollars, had been blown up by a mine without laying blame on any person or nation in particular, but public opinion in the United States blamed the Spanish military occupying Cuba anyway.



Subsequent diplomatic communications failed to resolve the matter, leading to the start of the Spanish American war by the end of April.
Source: Britannia