Given the colossal egos involved, I think that all of the leaders, with certain foreknowledge, would have still embarked on war; certain that THIS time they would win. After all, there was honor and chivalry at stake. They all thought of war as something noble. They had a mindset and world view that is hard to fathom today.
There was a wonderful series on YouTube called
“The Great War,” that followed the war week by week.
https://www.youtube.com/watch?v=FrCOKVnBxBM
A good series on the path to WWI - BBC series “ A Fall of Eagles”. It was shown in the US in the 1970s. You can buy it off Amazon. Its based on a book of the same title. The book is interesting because it has a lot of interviews with the grandchildren. The interviews had - “grand-papa this & grand-mama that”.... it all sounded very familiar and ordinary....very human & very sad!