[citation needed]

Friedrich Engels was born on 28 November 1820 in Barmen, Jülich-Cleves-Berg, Prussia (now Wuppertal, Germany), as eldest son of Friedrich Engels Sr. (1796–1860) and of Elisabeth "Elise" Franziska Mauritia von Haar (1797–1873).[10] The wealthy Engels family owned large cotton-textile mills in Barmen and Salford, both expanding industrial metropoles. Friedrich's parents were devout Pietist Protestants[5] and they raised their children accordingly.

In Manchester, Engels met Mary Burns, a fierce young Irish woman with radical opinions who worked in the Engels factory.[25][26] They began a relationship that lasted 20 years until her death in 1863.[27][28] The two never married, as both were against the institution of marriage. While Engels regarded stable monogamy as a virtue, he considered the current state and church-regulated marriage as a form of class oppression.[29][30] Burns guided Engels through Manchester and Salford, showing him the worst districts for his research.

Mary Burns (29 September 1821[1] – 7 January 1863)[2][3][4] was a working-class Irish woman, best known as the lifelong partner of Friedrich Engels.[5][6]

What does this have anything to do with Engels? You claimed Engels married a Rothschild.

Did a quick search, also no Rothschild.