Auxilia, otherwise known as 'feudal aids', was a form of taxation levied under the feudal system. The auxilia were due to the Crown when a king's son was granted knighthood, when a royal daughter was married, and when a member of a royal family needed to be ransomed.
The most obvious example of this last was when a ransom was needed to free Richard the Lionheart from captivity. The auxilia was payable by all those who held land directly from the king - in effect this would apply to powerful members of the nobility, and to certain monastic lands, though it could in theory apply to poorer classes as well.
Time period(s): Medieval