Agreed! These were the WW2 Germany's "Lost Legions" / Publius Quinctilius Varus and the Battle of the Teutoburg Forest. Expansion can and does continue but it is more momentum and the hollow military becomes the norm and the foot soldier knows it to his bones!
A good ficitonal book about Kursk is the “Last Citadel” by David Robbins:
“The battle for the Soviet city of Kursk in July 1943 during World War II involved two million soldiers. Code-named Citadel, it was Hitler’s frenzied—and final—attempt to defeat Russia on the eastern front and was the largest buildup of German armed power of the war. Robbins re-creates the battle in this rousing novel: its characters being Hitler; his generals and advisers; Russian, German, and Spanish foot soldiers and tank drivers; fighter pilots (both men and women); partisans; and even elderly men and women digging trenches. Robbins, author of War of the Rats (1999) and Scorched Earth (2002), has done extensive research into the weapons and planes used in the battle, bringing to life the horrors of war”