Such was the carefully digested scheme of military defence bequeathed to his successors by Constantine, who doubtless anticipated that he had granted a lease of endurance to the regenerated Empire for many centuries to come. But in the course of a hundred and fifty years this fine system fell gradually to pieces; and by the beginning of the sixth century no more than a _cento_ of the original fabric can be discerned in the chronicles of the times. The whole forces were diminished almost to a moiety of their full complement;[706] the great peripheral bulwark of the _Limitanei_, scarcely discoverable on the Illyrian frontier, in other regions was represented by meagre bodies of one or two hundred men;[707] whilst the _Palatines_ and _Comitatenses_ betrayed such an altered character that they could claim merely a nominal existence.[708] The very name of legion, so identified with Roman conquest, but no longer available in the deteriorated military organization, became obsolete. In a Byzantine army at this period three constituents exist officially, but with little practical distinction. They appear as the _Numeri_,[709] the _Foederati_, and the _Buccellarii_. 1. The _Numeri_ are the regular troops of the Empire, horse and foot, enrolled under the direct command of the Masters of the Forces, but the principle of strict selection has been virtually abandoned, applicants are accepted indiscriminately,[710] and even slaves are enlisted and retained under any plausible pretext.[711] 2. The _Foederati_ now consist of bodies of mercenaries raised as a private speculation by soldiers of fortune, with the expectation of obtaining lucrative terms for their services from the Imperial government.[712] Such regiments were formed without regard to nationality, and might be composed mainly, or in part, of subjects of the Empire, or be wholly derived from some tribe of outer barbarians who offered themselves in a body for hire. On being engaged, each band received an _optio_ or adjutant, who formed the connecting link between them and the central authorities, and arranged all matters relating to their _annones_ and stipend.[713] But the tie was so loose that even on a foreign expedition they might arbitrarily dissolve the contract for some trivial reason, and possibly join the enemy’s forces.[714] 3. The _Buccellarii_[715] are the armed retainers or satellites of the Byzantine magnates, whether civil or military, but especially of the latter. Officially they are reckoned among the _Foederati_,[716] and are obliged to take an oath of allegiance, not only to their actual chief, but also to the Emperor.[717] Their number varied according to the rank and wealth of their employers, and in the case of the Praetorian Praefects, or the Masters of the Forces, might amount to several thousands.[718] In each company they were divided into two classes, named respectively the lancers and the shieldmen. The former were selected men who formed the personal guard of their leader, the latter the rank and file who were officered by them.[719] The lancers were invariably cavalry, the shieldmen not necessarily so. These satellites were recruited preferably amongst the Isaurians,[720] a hardy race of highlanders, who, though within the Empire, always maintained a quasi-independence in their mountain fastnesses, and devoted themselves openly to brigandage.[721] To check their depredations a military Count was always set over that region, which thus resembled a frontier rather than an interior province. A fleet of warships was not kept up systematically at this epoch, but in view of an expedition, owing to the small size of the vessels, a navy could be created in a few weeks.[722]