The rules used were fast play grand armee (available for free). Each base is a brigade sized formation. The figures on the base represent the strength points, and are removed/knocked down as the unit takes damage. Commanders randomly generate 'command dice' which are used to keep your commanders doing as you wish, rather than taking a withdraw/hold/attack posture (usually at the worst time). Turns are random number of pulses (up to 4), so you need to parcel out the command dice steadily, as longer turns can create issues for command as the control runs thin.
Early morning sees the french advance their guns to the river line, and sustained musketry and a charge remove the first prussian defender. The cavalry on in the East are identified as the imperial guard heavy cav. Worst yet, Napoleon has appeared! He obviously believes this is an important engagement.
The heavy cavalry hasn't had a crushing victory, damaging but not destroying the light cav facing them. They will suffer a counterstrike from the prussians inflicting a tough attritional battle.
As the sun hits its zenith, Napoleon receives ADC's arriving on the field with fresh messages. He looks at them, stares at the battlefield between narrowed eyes, and hands command back to the local commander. Taking his bodyguard he gallops back East, heading towards a more pressing engagement.
The battle drags on to the late afternoon, but it has been obvious the outcome for some time. The french cavalry seize the crossing to the west and lurk in the north.
At last the Prussians break, and take a modest amount of damage in the pursuit. It's unlikely whether the survivors have any viable path to escape. The Prussians have definitively placed Napoleon Bonaparte, perhaps giving some indication of his master plan. But where has captured his attention such that he has left the battle at noon. Where will the Corsican ogre strike next?