It was primarily the "sinking of the USS Maine" that was used as a reason to go to war with Spain in the Spanish-American War, since this was blamed on the Spanish.
"Remember the Maine" became a popular rallying cry for those people who wanted to go to war with Spain. When it was sunk in Havana Harbor, many Americans believed it was the work of the Spanish, but the exact cause of the explosion that sank the ship is not known.