Under the feudal system the idea prevailed that the vassal's purse as well as his body was to be at the lord's service. Originally the right to draw upon his vassals for money was exercised by the lord whenever he desired, but by custom this ill-defined power gradually became limited to three sorts of occasions when the need of money was likely to be especially urgent, i.e., when the eldest son was knighted, when the eldest daughter was married, and when the lord was to be ransomed from captivity. In the era of the crusades, the starting of the lord on an expedition to the Holy Land was generally regarded as another emergency in which an aid might rightfully be demanded. The following extract from the old customary law of Normandy represents the practice in nearly all feudal Europe. Source--_L'Ancienne Coutume de Normandie_, Chap. 35. [Sidenote: The three aids] In Normandy there are three chief aids. The first is to help make the lord's eldest son a knight; the second is to marry his eldest daughter; the third is to ransom the body of the lord from prison when he shall be taken captive during a war for the duke.[327] By this it appears that the _aide de chevalerie_ [knighthood-aid] is due when the eldest son of the lord is made a knight. The eldest son is he who has the dignity of primogeniture.[328] The _aide de mariage_ [marriage-aid] is due when the eldest daughter is married. The _aide de rancon_ [ransom-aid] is due when it is necessary to deliver the lord from the prisons of the enemies of the duke. These aids are paid in some fiefs at the rate of half a relief, and in some at the rate of a third.[329] (_b_) MILITARY SERVICE From whatever point of view feudalism is regarded--whether as a system of land tenure, as a form of social organization, or as a type of government--the military element in it appears everywhere important. The feudal period was the greatest era of war the civilized world has ever known. Few people between the tenth and fourteenth centuries, except in the peasant classes, were able to live out their lives entirely in peace. Of greatest value to kings and feudal magnates, greater even than money itself, was a goodly following of soldiers; hence the almost universal requirement of military service by lords from their vassals. Fiefs were not infrequently granted out for no other purpose than to get the military service which their holders would owe. The amount of such service varied greatly in different times and places, but the following arrangement represents the most common practice. Source--_Les Etablissements de Saint Louis_, Bk. I., Chap. 65. Text in Paul Viollet's edition (Paris, 1881), Vol. II., pp. 95-96. [Sidenote: The conditions of military service]