You know, you TRY to reason with them on this.
The US had more casualties during the civil war (both sides) than WW2. Which happened before or after 1914?
When was the last time a plague wiped out 1/3 of Europe's population? Would that be before or after 1914?
When was the last time several nations existed in a state of declared war for ONE HUNDRED YEARS? Again, before or after 1914?
The WTBTS can just play on the whole 'world was a paradise before 1914' angle because the knowledge of history in this country is AWFUL. I mean, people are really, REALLY stupid as far as pre-20th century history goes - not just JWs, everybody! (Which probably is why it is so easy for them to gain new converts) The most extensive knowledge your 'common American' has on pre-20th century history comes from the movie renditions of the Jane Austen novels. Hardly a clear picture into this era!