It's far too late to get into this in any particular detail, but what strikes me about this passage is that it is based on a false premise. Natural rights need not be justified on the basis of conquest. What of the Lockean man who has gained the land on the basis of his labour?On another thread I was asked to give some of the arguments for collective ownership of the land of our Nation. It was too far off topic in that thread, so I decided to open a new thread here.
Marx writes in his Memorandum for Robert Applegarth, December 3 1869:
"While not intending to discuss here all the argument put forward by the advocates of private property in land — jurists, philosophers, and political economists — we shall only state firstly that they disguise the original fact of conquest under the cloak of "natural right". If conquest constitutes a natural right on the part of the few, the many have only to gather sufficient strength in order to acquire the natural right of reconquering what has been taken from them."
In these few words, Marx completely demolishes any question of their being any "natural right" to landed property. Clearly if the few have the "natural right" to expropriate land by force, so do the many.