Throughout both Northern and Southern Germany, where the minute distinctions of birth were guarded with the most jealous care from a very early period, the codes of the thirteenth century, including even the burgher laws, provided that a difference of rank permitted the superior to decline the challenge of an inferior, while the latter was obliged to accept the appeal of the former. So thoroughly was this principle carried into practice, that, to compel the appearance of a _Semperfri_, or noble of sixteen quarterings, the appellant was required to prove himself of equally untarnished descent.[449] In the same spirit a Jew could not decline the appeal of battle offered by a Christian accuser, though we may safely infer that the Jew could not challenge the Christian.[450] So, in the Latin kingdom of Jerusalem, the Greek, the Syrian, and the Saracen could not challenge the Frank, but could not, in criminal cases, decline his challenge, though they might do so in civil suits.[451] In Aragon, no judicial duel was permitted between a Christian and a Jew or a Saracen,[452] while in Castile both combatants had to be gentlemen, quarrels between parties of different ranks being settled by the courts.[453] On the other hand, in Wales, extreme difference of rank was held to render the duel necessary, as in cases of treason against a lord, for there the lord was plaintiff against his vassal, and as no man could enter into law with his lord, the combat was considered the only mode of prosecution befitting his dignity.[454] A question of this nature was the remote occasion of the murder of Charles the Good, Count of Flanders, in 1127. Bertulf, Provost of the church of Bruges, was rich and powerful, although in reality his family were villeins of the count. He married his nieces to knights, one of whom, in presence of the count, appealed another knight to battle. The appellee refused on the ground that he was not obliged to notice the challenge of a villein, for according to the law of the land a freeman marrying a serf was reduced to the latter condition after the expiration of a year. The Count’s attention being thus called to his rights over the family of Bertulf, he proceeded to establish them, when Bertulf set on foot the conspiracy which ended in the assassination of the count.[455] * * * * *