I disagree.
In 1870/71, the key to prussian-german victory was not diplomacy but the fact that Prussia had much better logistics and enjoyed the benefits of national conscription that gave it more trained soldiers.
At the beginning of the conflict, Germany had twice as many soldiers as France : 500.000 against 265.000. After general mobilization was completed, Germany had 1.2 million men under arms, while France had 900.000.
And Germany enjoyed a railroad network that allowed it to bring quickly fresh reinforcements on the battlefront. While France did not yet.
That was the key to prussian-german victory in 1870/71.
Germany had more troops and better logistics precisely because France had no allies and Germany could direct its resources on a single front. Not a coincidence that when it had to divide its resources in WWI and WWII it lost.
And who created the conditions that led to the Entente? Germany launched a futlie naval arms that alienated Great Britain and pushed them towards France. Thye had treaties with Russia and chose to abandon them. Willhemine Germany was the architect of it's own misfortune.And if Germany triggered WWI, it was not completely irrational. Germany did so, while it already was number one power on the continent, because it calculated that Russia was growing and modernizing so fast and that Austria-Hungary was fragile, that the balance of powers would shift to the benefit of the Entente in the future.
History suggests that post-Bismarck Germany was economically, industrially and militarily powerful, but diplomatically and stratefically ill led and run.
Post 1871 war with France, there was no need for an aggressive German foreign policy, naval race with Britain, nor their silly race for empire in Africa/Asia. One can almost envision German industrialists pleading with the Kaiser to be left to dominate Europe through economic power, without need for aggressive militarism.
Russia and Great Britain were essentially zero threat to Germany. France might have wanted revenge for 1871 but in the absence of allies that wouldn't have gotten anywhere. In both world wars a cadre of people with a desire for 'empire' and 'glory' led Germany to disaster.
Last edited: