The Red Cross was founded as a result of the Austro-Sardinian War (in particular the battle of Solferino).
The First and Second World Wars were important for women's lib. (although some posters might not consider that a good thing )
The sinking of the Titanic lead to the monitoring of icebergs (and perhaps improvements in safety measures on ocean liners).
Tests for colour blindness were divised after train crashes in Sweden (colour blind engineers could not see the difference between the red and green signs)
The North Sea Flood of 1953 led to the development of new technologies in waterdefences.
Napoleon's occupation of Europe left a legacy in legal systems and in science (metric system etc.).