Having scoured the net in the hope of finding a translation of the original French, despite my feeling that - as it is presumably a less well-known quote of the French gentleman - you as a competent translator should feel free a) to offer up a translation yourself, from the original French if possible, or b) consider translations from others - I can almost feel the avalanche at the back of my neck - such as myself along the lines of:
"The spirit of the Revolution, whose span encompassed the advances of the Imperial Guard, was (yet) to outlast its troops' demise/was (yet) to outlive the death-blow to its ranks."

Otherwise, you might wish to wait in the hope that someone has a translation of the book, which is admittedly far easier to open but, depending on the glossary, may not yield up the translation so willingly.

Cheers anyhow!