Prussian Army of the Napoleonic Wars
The Prussian Army of the Napoleonic Wars underwent a profound transformation between 1806 and 1815. Before 1806, the army was characterized by an inflexible command structure, reliance on an aristocratic officer corps, strict discipline, and tactics developed during the era of Frederick the Great.
Source: Wikipedia — Prussian Army of the Napoleonic Wars (CC BY-SA 4.0)