The Lord and vassal were interlocked in a bunch of mutual rights and obligations, to the advantage of both. Where the lord owed his vassal protection and the vassal owed his lord a specified number of days annually in military service and supplies of goods, and the lord was expected to provide a military for his king. With that feudalism was a political as well as military institution, one based upon a contract between two individuals, both of whom held rights in the land one worked. Because the military service of the KNIGHTS was a central element of feudalism, they made things like the introduction of heavy cavalry during the 8th century and the introduction of the stirrup, which greatly increased the efficiency of fighting on horseback for the knights the Long bow. With that the knight had to be able to maintain expensive equipment and a horse, and with that he would have to practice fighting and teach others how to fight as he got older. So to do that he needed a great deal of wealth to do this if he was supported by the work and labor of his people. The way feudalism works it resembles a pyramid, at the lowest are the vassals ((serf or peasants ) at its base and the true life of the whole thing) and, above them are the lines of authority the knights and, then the lord and, flowing up to the peak of the structure is the king. Common in all, was the process by which one nobleman (the vassal) became the man of another (the lord) by swearing homage and faithfulness to the lord, with some kind of oath like this one ( An Anglo Saxon Form of Commendation [from Schmidt: Gesetze der Angelsachsen, p. 404] ) "Thus shall one take the oath of fidelity: By the Lord before whom this sanctuary is holy, I will to N. be true and faithful, and love all which he loves and shun all which he shuns, according to the laws of God and the order of the world. Nor will I ever with will or action, through word or deed, do anything which is unpleasing to him, on condition that he will hold to me as I shall deserve it, and that he will perform everything as it was in our agreement when I submitted myself to him and chose his will.