The 100 Years' War w/ Joan of Arc helped contribute to the decline of feudalism by helping to shift power from the feudal lords to monarchs and common people which ruined feudalism because it gave power to the common people, who were usually powerless.
The Growth of Markets/Towns
The plague spread across the Silk Road from China through fleas on rats to Europe and other places.
The Magna Carta
The Black Death, a.k.a, the Bubonic Plague helped contribute to the decline of feudalism because during the years of the plague, trade and commerce slowed down majorly. As Europe was recovering, they didn't rebuild their economy in the same way. The feudal lords no longer had most of the power, people started feeling more independent and it messed up feudalism.
The Magna Carta
The growth of markets/towns contributed to the decline of feudalism because peasants or serfs or common people started to farm off of the manors land and sell the things they were growing. They were becoming more independent and towns and markets began to sprout up around the manors, which caused feudal lords to lose power.
The angry nobles forced King John to put his seal on the Magna Carta, in Runnymede by a river.
The Magna Carta led to the decline of feudalism because the Magna Carta states that there are rights and liberties that not even the king is above. It also states that monarchs should rule with the consent of the governed. These reforms strengthened the English common law and the role of the judges and juries. All of these ideas form the basis for modern democratic institutions, which pushed out the idea of feudalism.