He advocated the equality of men and peace among nations, in the face of colonialism (which he abhorred). His first-person hero embodies all the ideals every true American has ever stood for since 4 July 1776. And yet he never captured the attention of the wide American reading public. Attempts at introducing translations of his 'Winnetou' novels, or other tales set in the West, have singularly failed.
Of course, there is no denying that the majority of situations, no less than the personnel described by this writer, clash with reality: Life, and fights, and problems as he depicted them as characterizing the Western half of the US in the 1860's and 1870's, are strangely anachronistic. That in itself, though, does not make any book unmarketable. (Otherwise, science fiction, as an example, would never have had a chance to flourish.) And whatever his deficiencies in any lopsided presentation of situations with their regard to historical probability, Karl May thoroughly compensates this by a startling accuracy in the topographical details in his stories (which he saw through the mind's eye only and visualized correctly) and by his gripping atmosphere of verisimilitude. Above all, it is the timeless, mythical lore he calls to life, masterly but unobtrusively, an enigmatical quality that has kept his works alive for over a century by now, in his home country and elsewhere. And precisely this is the overall feature that appeals to Americans as it does to Europeans.