Hint:some of these events involved spheres of influence and control over resources in eastern europe!
EDIT: If you understand German, here is a song from 1972 about these brutal cross-examinations:
> Franz Josef Degenhardt - Befragung eines Kriegsdienstverweigerers
> https://www.youtube.com/watch?v=WDTtMTcj8X0
Additionally, the participation of Germany in the first aggressive wars in Yugoslavia in 1999 and then in Afghanistan from 2001 on (before citizens were told that the Bundeswehr is only a defense army, and would never participate in an aggressive war) lead to a radicalization of another generation against the Bundeswehr - and yes, this generation eagerly listened to the above-mentioned horror stories of the older generations. It is even rumored that this next generation's radicalization against the Bundeswehr indirectly lead to the suspension of the compulsory military service in Germany in 2011.
But I think you should legally be able to answer if you can think of anything between 1914 and 1945 that is taught to Germans in schools that might cause younger Germans to feel some aversion towards preparing to fight a land war against russia in eastern ukraine? Anything that maybe resulted in the premature deaths of millions of young german men, initially volunteers who were solicited at the secondary school level?
Massive political differences and ultimate outcomes aside for each conflict, Germany becoming increasingly militarized has a poor track record when it comes to not getting extremely large numbers of teenage german boys killed in eastern Ukraine.