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The only way to get ordinary people in the various belligerents to go along with WW1 was to tell them it would be over quickly, 'over by Christmas'. This might sound realistic if your objective is Paris. And the last time Germany fought France (Franco-Prussian war) it was over quickly, a with a decisive German Victory. So France First is something you can sell.
If you stand on the defensive in the west and focus east from the start, it becomes hard to convince people you are going to win quickly. Or Easily. Moscow/St Petersburg is much further away than Paris and history isn't exactly littered with wars against Russia which were won quickly and easily.
Besides what Germany wanted most out of the war was non-european colonies, or 'a place in the sun' as the Kaiser liked to phrase it. That and putting a permanent end to French ability to pose a meaningful threat to Germany. You get that from defeating France, not Russia.
... well .. sry ... but ...
T.H.E. first and most important narrative "convincing" esp. the german ordinary people was :
TO THE DEFENSE !!! we're attacked from all sides and the only way to secure survival is to beat the enemieS (it was well known to everybody that the enemies were everywhere at the same time (at least as perceived)
The narrative about the 'home by X-mas' was rather wishfull thinking and even more hoping on all sides involved esp. in decision making (
including the military lot behind Moltke that told the politicians only what they - the militaries as well as the politicians wanted to hear well aware THAT it was wishfull thinking)
And therefore everybody - esp. the german people - rather knew that they were working on "principle: HOPE".
The other way 'round than IOTL - defend in the west AS WELL as defending in the east but there with more ... 'mobility' of warfare (
enough and LAARGE enough gaps in the fortress 'ring' compared to the western borders) - was by many seen as viable. ... and spread far enough though the public by a number of publicists.
And : NO
what 'Germany' wanted most out of a war - a perhaps rather 'french' sounding wish esp. with the interwar times in mind ;-) - was: security
from being attacked from the east (the by everyone perceived in short time really indomitable juggernaut)
the by everyone (german public) perceived enemy danger numer one (it was Kaiser Bill - and his ... emotinal problems with king Edward VII and hus 'english family'and his lot seeing England as the No. 1 enemy being behind all the grow up on the german borders)
from being attacked from the west
attacking there first was ONLY seen viable as the preparation for ging finally east
from bein attacked on the streets of globality - or sea and trading lanes
This idea comes up a lot on this forum, but it wasn't practical.
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... your opinion ... and far from proven or even generally agreed upon (
aside maybe the questionabe 'practicalibilty of war' in general, but that is a ... lesson of us afterborne generations only and not the contemporaries we're talking about) and of many other 'western centrists'