"The marriage between Carl von Clausewitz and Countess Marie von Brühl was an unlikely partnership. A wealthy, cultured, politically-literate but plain woman with interests of her own, Marie's marriage to a less-fortunate, then-unknown officer in 1810 did not make sense by most accounts. But their relationship was forged by a love for each other, a deep sense of trust, and a meeting of the minds over common interests, one that would shape Clausewitz' opus, On War. Marie von Clausewitz is the first biography to shed light on Marie's illustrious life before she met Clausewitz and how she used her refined upbringing and social insights to inform his thoughts on warfare and politics. A newly-discovered archive of correspondence reveals details of their relationship and the extent of Marie's imprint on the theories that eventually comprised On War, from their courtship to the days of the Napoleonic War. This was a partnership - in the truest sense of the word, atypical for its time - and a