"Lions led by donkeys" is obviously an ideological slogan, meant to praise the common soldiers and blame (relative) failures on others, e.g. the Upper Class. It cannot possibly be true.

The only relevant dispute is about political justification. Bad politics resulting in warfare is condemnable, and would be so even if the military strategy had been optimal.

I have no doubt that some German military circles would have loved to dominate the world if deemed feasible. So would some military circles in most other countries, even today. If we were to accept "it's either them or us" (= our military leaders, not our people as a whole!), war would be inevitable, always. Fortunately, there is diplomacy. We must demand from our governments to excel in diplomacy, not allow them to profit from past false glory.