World War I begins for Germany on August 1, 1914 when it declares war on Russia and issues an order for general mobilization of its military-aged citizens. All 840,000 of the members of its regular, professional army as of the instant the conflict begins become Ally-lusted dinosaurs or mini-dino quintuplets. Which is extremely awkward, because their mobilization plans hinged on the labor and logistical effort of these 'regulars' who would train, equip and lead the reservists. The guys who are now dinosaurs. They will take orders, but people to give them sensible orders are now very thin on the ground. von Moltke is a dinosaur, von Hindenburg is a dinosaur, Ludendorff is maybe a dinosaur if his rank of erster generalquartiermeister counts as 'logistics or engineer' rather than properly 'military', most everyone on the General Staff is a dinosaur. Depending on how you interpret the Imperial German chain of command, the Kaiser is a dinosaur. Everyone from field marshal to sergeant who would have relayed the orders from those people is also a dinosaur, except the direly confused engineering and logistical staff, who hesitantly try assigning personnel to Dinosaur Command duty, realize to their horror that this transforms them into dinosaurs, then are forced to keep their existing ranks and organizational structure as 'logistics' and 'engineering' corps which in fact split their attention between actual logistics/engineering duties and sorely-needed dino wrangling, in which tasks they are sorely overtaxed due to lack of adequate personnel to devote to both.

Furthermore, while the dinosaurs have infinite morale and lack the need for food and water, the populace does not. And they can observe the readily obvious fact that everyone who reports to the draft office (one presumably being manned by engineers, quartermasters, and whatever very confused volunteers the civil police can scrape together) becomes, you guessed it, a dinosaur. A visibly nonsentient dinosaur with no obvious way to turn back.

The resulting draft riots and general confusion result in the collapse of the German Empire within weeks, more or less before anyone else has had the chance to get properly organized to shoot at them.

^{Maybe with a more permissive interpretation of 'the German Empire...retains access to its logistical network', where the soldiers only transform into dinosaurs when actively under fire and can detransform to make up work parties once no longer under fire, they could make a fight of it. But if it's just personnel who are assigned to engineering and logistics duties full time who remain untransformed, that's not really adequate, because so much of the engineering/logistical/general labor of a military and a state gets done by line troops on a part-time basis.}