These perpetual spoliations of the Christian cemeteries led to the 145 rapid destruction of many of their galleries and chambers, and to their final abandonment like a worked-out mine--a mine, too, which had been the source of greater riches to the church than treasures of silver or gold. In the removal of the relics of the martyrs the principal motive for the protection or adornment of the Catacombs was taken away, and during the gathering darkness of the Middle Ages they speedily passed out of the knowledge of mankind. In a few of those in the immediate vicinity of some church or monastery a subterranean chapel was still kept open, and an occasional mass was celebrated on the presumed anniversary of the martyr whose name was associated, often erroneously, therewith; or some zealous and adventurous pilgrim might even penetrate their obscure recesses. But a blight had fallen on the once beautiful Campagna. Desolation, pestilence, and death brooded over the deserted plain. Through the natural dilapidations of time, and the spoliations of Saracens, Normans, and Greeks, who successively invaded Italy and wasted the country with fire and sword, the basilicas and oratories of the Byzantine period crumbled to decay or were destroyed, and the monasteries were deserted; their cowled and sandaled occupants, long the sole custodians of the Catacombs, taking refuge within the city walls. The rains of a thousand autumns and the frosts of as many winters caused the crumbling of the _luminari_, the falling in of the roofs, and ruin of the galleries. The knowledge of the past was lost in the gathering gloom of the dark ages, so that in an enumeration of the Roman Catacombs in the fourteenth century only three are mentioned, and these were connected with some church. 146 In the fifteenth century but one, that of Sebastian, was known. Yet there is evidence that some of the galleries were accessible, and were used for dark and sinister purposes, in keeping with their gloomy and desolate character. During the lawless period from the eleventh to the fifteenth century, when faction and civil war and anarchy laid waste the country, and even the classic mausolea above ground were converted into armed fortresses, these gloomy vaults became the rendezvous of insurgents and conspirators, who feared no betrayal of their bloody secrets by the silent sleepers in their narrow cells. In their dark recesses were concocted those “treasons, stratagems, and spoils” that desolated the land. Frequently armed bands of the retainers of hostile houses--the Montagues and Capulets of the day--met in these subterranean battle-grounds, and the war-cry of Guelph and Ghibelline, of Colonna and Orsini, rang through the hollow corridors, disturbing the quiet of the graves. Bloodshed and cruelty often desecrated the spot sacred to religion and the ashes of the sainted dead. Petrarch thus describes these unhallowed uses of the Catacombs: