The spirit of Chivalry, however, led to a thousand deeds and habits not required nor regulated by any law. Were two armies opposed to each other, or even encamped in the neighbourhood of each other, though at peace,[64] the knights would continually issue forth singly from the ranks to challenge any other champion to come out, and break a lance in honour of his lady. Often before a castle, or on the eve of a battle, a knight would vow to some holy saint never to quit the field, or abandon the siege, till death or victory ended his design. Frequently, too, we find that in the midst of some great festival, where all the Chivalry of the land was assembled, a knight would suddenly appear, bearing in his hands[65] a peacock, a heron, or some other bird. Presenting it in turn to each noble in the assembly, he would then demand their oath upon that bird to do some great feat of arms against the enemy. No knight dared to refuse, and the vow so taken was irrevocable and never broken. One of the most extraordinary customs of Chivalry, and also one of the most interesting, was the adoption of a brother in arms.[66] This custom[67] seems to have taken its rise in England, and was in common use especially among the Saxons. After the Conquest, however, it rapidly spread to other nations, and seems to have been a favourite practice with the crusaders. Esteem and long companionship were the first principles of this curious sort of alliance, which bound one knight to another by ties more strict than those of blood itself. It is true the brotherhood in arms was often contracted but for a time, or under certain circumstances,[68] which once passed by, the engagement was at an end; but far oftener it was a bond for life, uniting interests and feelings, and dividing dangers and successes. The brothers in arms[69] met all perils together, undertook all adventures in company, shared in the advantage of every happy enterprise, and partook of the pain or loss of every misfortune. If the one was attacked in body, in honour, or in estate, the other sprang forward to defend him. Their wealth and even their thoughts were in common; so that the news which the one received, or the design that he formed, he was bound to communicate to the other without reserve. Even if the one underlay a wager of battle[70] against any other knight, and was cut off by death before he could discharge himself thereof, his brother in arms was bound to appear in the lists, in defence of his honour, on the day appointed. Sometimes[71] this fraternity of arms was contracted by a solemn deed; sometimes by a vow ratified by the communion and other ceremonies of the church. In many cases,[72] however, the only form consisted in the mutual exchange of arms, which implied the same devotion to each other, and the same irrevocable engagement.