You actually prove his point more than anything. The German Empire was very short lived in part because it attempted to impose a political order onto a variety

You actually prove his point more than anything. The German Empire was very short lived in part because it attempted to impose a political order onto a variety of ethnicities. The policy of germanizing these groups, Kulturkampf and its associated so-called 19th century Ostsiedlung (of "Drang nach Osten" fame) went hand in hand with the imperial drive to assimilate and subjugate its members culturally and religiously. The resulting resentment contributed to WWI. Despite certain national undertones during WWII, the major cause for WWII was imperial in nature, i.e., the attempt at reestablishing the German Reich, this time across Europe, as well as the expansion of the Russian Empire in the form of the Soviet Union which likewise tried to eradicate conquered nations and ethnicities in order to create a Soviet people (what some sarcastically call Homo Sovieticus). They failed. The latter, which managed to live on for another 50 years after WWII, failed in part because the idea of the Soviet people as buckling under the seething pressure of national and ethnic difference and consciousness.