The "Otranto Disaster" took place when the "SS Otranto" was rammed by another troop ship off the coast off the Isle of Islay.
The Sepoy Rebellion was mainly a rebellion against the imposing rule of the British East Indian Company in India--which many local Indians felt was both economically and morally unfair. It led to a wide-spread British reorganization of the political and military institutions in India in an effort to have more of a solidified rule.
25,000 Mexican troops and civilians and many Americans died from a virus
It was the Kansas-Nebraska Act that led up to the disintegration of the Whig Party.
