When we come to the chroniclers of the middle of the 10th century we find a marked difference. It is true that the words _castrum_, _castellum_, _municipium_, _oppidum_, _munitio_, are still used quite indifferently by Flodoard and other writers for one and the same thing, and that in a great many cases they obviously mean a fortified town. But there are other cases where they evidently mean a castle. And if we compare these writers with the earlier ones in the same way as we have already compared the pre-Conquest portion of the _Anglo-Saxon Chronicle_ with the chroniclers of the 11th and 12th centuries, we find the same contrast between them. In the pages of Flodoard or Ademar the action constantly turns on the building, besieging, and burning of castles, which by whatever name they are called, have every appearance of being private castles. In fact before we get to the end of the century, the private castle is as much the leading feature of the drama as it is in the 11th or 12th centuries. Why, then, had the chroniclers no fresh word for a thing which was in its essential nature so novel? The obvious and only answer is that the private castle in its earlier stages was nothing more than an embankment with a wooden stockade thrown round some _villa_ or farm belonging to a private owner, and was therefore indistinguishable in appearance, though radically different in idea, from the fortifications which had hitherto been thrown up for the protection of the community.[175] How easily we may be mistaken in the meaning of the word _castellum_, if we interpret it according to modern ideas, may be seen by comparing the account of the bridge built by Charlemagne over the Elbe, in the _Annales Laurissenses_, with Eginhards narrative of the same affair. The former states that Charlemagne built a _castellum_ of wood and earth at each end of the bridge, while the latter tells us that it was a _vallum_ to protect a garrison which he placed there. This, however, was a work of public utility, and not a private castle. But scanty as the evidence is, it all leads us to infer that the first private castles were fortifications of this simple nature.[176] Mazières-on-the-Meuse, which was besieged for four weeks by Archbishop Hervey, took its name from the _macerias_ or banks which Count Erlebald had constructed around it. It is impossible to say whether this enclosure should be called a castle or a town, but in idea it was certainly a castle, since it was an enclosure formed for private, not for public interests.