The centenary commemorations for World War One are a chilling reminder of how quickly a continent can slip from a long peace to industrial slaughter. I'm inclined to agree with the current orthodoxy on the causes of the war- that it was a result of German military expansionism.
Whether the UK should have entered the war is harder to say- if the Asquith government had stayed out, Germany would likely have won and an unrestrained aggressive nation could well have threatened Britain- with no France or the Low Countries between Germany and the UK. Yet it's hard to imagine any greater damage would have been inflicted than hundreds of thousands dead that were inflicted.
An awful even but one that offers no easy lessons.