Bee (my son Anno's mum) asks much the same question in a little video I shot when we visited George's grave in 1984:
http://www.youtube.com/watch?v=umWkq94gUWY
A huge difference, one imagines - but then again, if George had survived the whole of WW1, he would have brought home some pretty grim memories, which might in turn have led to increasing bouts of melancholy... he was already touched with a sense of weltschmertz. Would he have prevented Peter committing suicide? I sort of doubt it, given that Peter's depression was fuelled by watching his poor wife Pee increasingly suffering the ravages of Huntington's chorea ...