The French invasion of Switzerland and establishment of the Helvetic Republic in 1798 drove Bonstetten once more into private life. At the invitation of Madame Brun, he resided in Copenhagen, Denmark, until 1801. He then traveled to Italy before settling in Geneva for the remainder of his life. He resided there uneventfully but in the society of many distinguished people, including Madame de Staël. His most celebrated book—"Men of the South and of the North" (")—was published during this era, arguing that climate was responsible for the superiority of northern Europe over the south, but his own writing generally fell into low esteem. Instead, he is principally remembered for his social character—as a conversationalist, and as the friend, often the intimate companion of many of the more celebrated leaders of thought and action during his long life.