Born in Hamburg, she was the eldest daughter of a prominent Jewish physician, David Assur, who converted to Christianity upon marriage to her Lutheran-raised mother, and changed his name to Assing. Her mother was the poet Rosa Maria Varnhagen Assing, who was friendly with other literary women, including Clara Mundt and Fanny Lewald, and prominent in liberal circles that supported (but failed to achieve) social revolution in 1848.
Her aunt Rahel Varnhagen was a noted salon host. Ottilie and Ludmilla soon came to blows in that household, and Ottilie left, never to return. In 1852, she emigrated to the United States, settling in New York and eventually in Hoboken, New Jersey.
She supported herself by writing articles for the Morgenblatt für gebildete Leser and often wrote under a male pseudonym.
Assing read the Narrative of the Life of Frederick Douglass, and was impressed. In 1856, she went to Rochester to interview Douglass.
They struck up an immediate friendship. Over the next 28 years, they attended some meetings and conventions together.
At first, she wrote general interest pieces about culture, but soon her writing focused on the abolitionist movement.
While Assing was in Europe, trying to establish her claim to her sister"s estate (including her mother"s, and the Varnhagens" papers) she read in a newspaper that Douglass was to marry his 20-years-younger white secretary, Helen Pittsburgh She had already been diagnosed with incurable breast cancer. In 1884, Assing committed suicide with cyanide in Paris in a public park.
