Prince Antoni Radziwiłł. Their meeting came less than a year after Brühl's father's unexpected death due to complications from liver disease in July 1802. The two had a lengthy courtship for various reasons; one being her mother's disapproval of the relationship with a man of lesser social standing. Clausewitz had no inheritance and would have to rely solely on his lieutenant's pay, which was not enough to support a family. To marry without her mother's blessing would not have been legally possible. Marie, herself, was hesitant to commit to the relationship and had to consider all the circumstances surrounding the courtship. She was in her late twenties when the correspondence began between Carl and herself. This was considered past high society's "marrying age." Yet Brühl was one of the few unmarried women during that time who earned an income on her own. She did not want to lose, what she referred to as, her "inner freedom." The two made their relationship official in May 1806. In August 1810, Clausewitz received an important letter from Friedrich Wilhelm that promoted him to the rank of major, and gave him official permission to marry. On 17 December 1810, Brühl married Clausewitz. The two frequently discussed politics, literature, current events together. They considered each other equals, which was rare for a man to think of regarding his own wife. Carl and Marie were unable to conceive children. Present day theories point to Carl's chronic illness as the culprit. The two were married for a total of 21 years, up until Clausewitz's death. From 1832 to 1834, following Clausewitz's unexpected death from cholera in 1831, she edited and published several of his books, including his most famous one, On War. Throughout their correspondence, Marie insisted that Carl send her his drafts and notes for safekeeping. He was known to have an unorganized writing process that would often lead to lost papers and unfinished ideas. In fact, when Carl was writing On War, Marie acted as the researcher and copywriter for the book. Marie's handwriting can be found on some of the pages of the On War manuscript, listing notes and references. Additionally, Brühl wrote a preface to On War. In the summer of 1832, less than a year after Carl's death, a publishing house in Berlin had put out announcements advertising the upcoming publication of On War. With the help of her brother, Marie transcribed