The Lost Generation was the first rebellious youthful generation. Impacted by the horrors of WWI, they could not avoid a second world war, but their new ideas and stances caused changes decades later. 

Did the Lost Generation define the time they lived in? 
I believe so. If only for a short decade. 
Their extremely innovative concept of life, caused by an extremely ‘innovative’ war, was – I believe – extremely ahead of time. 
The Lost Generation’s caesura with the values and accepted behaviours of the previous generation was a shock reaction to the unexpected movements and events of the Great War. 
The depths to which the Great War brought these people were so deep that it caused thoughts and feelings their time was unprepared to accept. 

The men and women of the Lost Generation came together in life in the same way they came together on the battlefield: almost like equals, knowing what they could do, being willing to do it, and indeed having done it. 
These men and women were willing to consider every person for their value, not for their gender or their culture and origin. They were willing to experiment with new ways of coexistence. 
Their openness to the future was almost as large as their disillusionment. 

Unique circumstances allowed the Lost Generation to exist and impact their time. Those circumstances had already changed in the 1930s, ten short years after the end of the Great War. What the Lost Generation wanted was already not possible a decade after the war. 

And maybe they be aware of it in their subconscious. 
This may be why they were so disillusioned about the future and didn’t believe in their own rebellion. 
Maybe, deep down, they knew that the world needed to change, but it was not ready to do so yet. 

Did they also imagine a second world war? 
Possibly. 
Some people—especially politicians and sociologists—knew that the Great War was not over and the European Civil War was ongoing. The general political and social unrest must have suggested to them that they were not out of it. 

This may be why the Lost Generation was so disillusioned. This may be why they wanted to live life so intensely while they could. 

Yet, their rebellion, their willingness to express it (when they could), and the very fact that they incarnated it weren’t for nothing. 

The change they caused might not have been able to stop a second terrible world war that was probably unavoidable, but the seeds they planted would survive it and bloom even decades later. 

We still owe a big deal of who we are to this generation of men and women who suffered and fought and did what they could to leave a message for us—a message—I believe—of peace, equality, and freedom.