Prussian Landwehr which is said to have paved the the way for NAP's defeat at Waterloo by running so fast back to old Deutschland that Grouchy believed that they represented the main German army.
Your history lessons must have taken place either on a different planet or in an alternate history.
Or you are French. They constantly ignore the battle of Wavre for two centuries now...
No offense, just kidding
I wrote "is said". And it was--at least partly-- regular Prussian regimentsb that fought at Wavre. But what induced Grouchy to place his corps on the wrong side of the Prussians?
I can for an eyewitness to Wavre recommend Wilhelm Tetschke's "Wir Habern auch in Kanonendonner gestanden"-- a Prussian student who fought at Wavre, although in the regular army. Especially toucjing is his chapter "Grouchy siegt", when they believed that everything was lost. They only heard about Napoleon's defeat at the rendesvous point in Brussel.
Maybe you just misunderstood my point which was that the Landwehr were not the most stable of troops in the Prussian army. I did not write that the the new tregularf Prussian army ran from anything.