I'm reading Waterloo - New Perspectives by David Hamilton-Williams This is a fairly recent (1993, revised edition 1999) reappraisal of that battle. The author was able to get access to 700 letters which hadn't been looked at in toto for 190 years. These letters had been solicited immediately after the battle from the participating English officers to create a model layout of the unit dispositions during the battle. As it turns out, the officer creating the layout, Captain William Siborne, only used those letters sent to him by officers who were willing to pay to be included....less than 200 of them. No Dutch, French, or Prussian officers were contacted. This secret was kept by Siborne's family for over a hundred years, and they would not release the letters to other scholars. For over a century, the Siborne account was taken as gospel and used as the basis for countless other books. These first person accounts languished in archives for nearly another century. This book has more details about the battle than any other I have seen, and is nearly 180 degrees on unit dispositions from earlier works. That said.... I was struck by one short passage:

By 15 June, 234,720 National Guardsmen had been summoned, and 150,000 were already assembled. From his surplus of regular army officers on half pay, Napoleon assigned many to train the National Guard up to regular army standards. He well remembered how, at La fere-Champenoise in 1814, a division of these untrained men had blundered into the entire Allied army. The division assumed a square formation and fought a stubborn retreat for sixteen miles, assailed by almost the whole of the Allied cavalry, 20,000 horsemen. The Guards were only compelled to surrender when the entire Russian and Prussian Guard infantry blocked them and reduced them by cannon fire.

Here is another more detailed account:

At dawn on the 25th, then, the allied Grand Army turned to the right-about, while Bluecher’s men marched joyfully on the parallel road from Chalons. Near La Fere-Champenoise, on that day, a cloud of Russian and Austrian horse harassed Marmont’s and Mortier’s corps, and took 2,500 prisoners and fifty cannon. Further to the north, Bluecher’s Cossacks swooped on a division of 4,500 men, mostly National Guards, that guarded a large convoy. Stoutly the French formed in squares, and beat them off again and again. Thereupon Colonel Hudson Lowe rode away southwards, to beg reinforcements from Wrede’s Bavarians. They, too, failed to break that indomitable infantry. The 180 wagons had to be left behind; but the recruits plodded on, and seemed likely to break through to Marmont, when the Czar came on the scene. At once he ordered up artillery, riddled their ranks with grapeshot, and when their commander, Pacthod, still refused to surrender, threatened to overwhelm their battered squares by the cavalry of his Guard. Pacthod thereupon ordered his square to surrender. Another band also grounded arms; but the men in the last square fought on, reckless of life, and were beaten down by a whirlwind of sabring, stabbing horsemen, whose fury the generous Czar vainly strove to curb. “I blushed for my very nature as a man,” wrote Colonel Lowe, “at witnessing this scene of carnage.” The day was glorious for France, but it cost her, in all, more than 5,000 killed and wounded, 4,000 prisoners, and 80 cannon, besides the provisions and stores designed for Napoleon’s army. Nothing but the wreck of Marmont’s and Mortier’s corps, about 12,000 men in all, now barred the road to Paris. Meeting with no serious resistance, the allies crossed the Marne at Meaux, and on the 29th reached Bondy, within striking distance of the French capital.

The French weren't always wimps.