Under feudalism in England, society was strictly hierarchical. The king was at the top and granted land (fiefs) to lords in exchange for their loyalty and military service. Serfs farmed small plots of land belonging to the lords and gave a portion of their crops in return. Feudalism established obligations of loyalty from everyone to the king and was reinforced by a code of chivalry that knights pledged to follow. It was weakened over time by events like the Magna Carta and the Black Death.