 He had "official" homes and "unofficial homes" all over Salford, Weaste and other inner-city Manchester districts where he lived with Mary Burns under false names to confuse the police.Little more is known, as Engels destroyed over 1,500 letters between himself and Marx after the latter's death so as to conceal the details of their secretive lifestyle.Despite his work at the mill, Engels found time to write a book on Martin Luther, the Protestant Reformation and the 1525 revolutionary war of the peasants, entitled "The Peasant War in Germany".