This is a POD I remember discussing back in my days over on shwi, many moons ago, but still an interesting one:
6 Aug, 1914: The German 14th Brigade might legitimately regard themselves as unlucky. Not only are they currently taking heavy casualties in their efforts to capture the Belgian fortifications around Liege; not only has their commanding officer, Generalmajor Friedrich von Wussow, been killed in action, but so has that dashing General Staff observer, Generalmajor Ludendorff, who had assumed command in the aftermath...
So, Erich Ludendorff is killed in the siege of Liege, 1914. I think it's fair to say that this could have massive consequences for Germany's conduct of the rest of the Great War, maybe not immediately (although if the sieges of Liege and Namur suffer delays compared to OTL, that might do interesting things to the campaigning in France during 1914), as Tannenberg was, if I understand correctly, pretty much already planned out by Hoffmann and others by the time H&L showed up to hog the glory, but certainly by 1916, assuming things adhere closely enough to OTL for Hindenburg eventually to be named Chief of the General Staff.
The really key factor will be whoever gets sent along to East Prussia with Hindenburg ITTL. Does anybody have any ideas on who might be the most likely candidate? Of course, Ludendorff's eventual successor, in OTL 1918, was Wilhelm Groener - if he becomes Hindenburg's right hand man in 1914 that could have a very interesting effect on the outcome of the war, given his willingness in OTL to cooperate with the SPD and the fact that he's generally saner (but maybe not as brilliant?) than Ludendorff in every possible way...
Iirc, in 1914 Groener was the German Army's top railway guy. And he wasn't Prussian either (a Wurttemburger, I think?). Does this rule him out completely as a choice to help command the last-ditch defence of East Prussia from the Slavic Horde? (I seem to remember some suggestion that Hindenburg's extreme Prussian-junker image was one factor in him being picked for the Tannenberg gig. That and the fact that he lived near the main railway line from General Staff HQ to East Prussia...or something like that...)
So, thoughts, anyone?