The Brienne line is one of the earliest direct descendants of William the Conqueror. 
The ancestors of Margaret Fiennes (1269-1334) ties to the line of William Fiennes (1357-1402) with the grandparents of Margaret and the great great grandparents of William. Those common ancestors are Enguerrand Fiennes and Isabel Conde. See https://fabpedigree.com/s048/f082772.htm and https://fabpedigree.com/s077/f375094.htm

Historical
1262: Norway, Iceland, Greenland - King Haakon IV of Norway annexes Iceland and Greenland to end a civil war in Iceland
1263: Scotland, Norway - Norsemen ejected from Scotland
1265: England - Edward I (Longshanks) defeats Barons at Evesham in the Barons War (1264-67)
1266: Italy, Turkey, Bulgaria - Venetians Niccolo Polo and brother Maffeo Polo make trade expedition to Constantinople, and then east to Bolgara and then Sarai, in the Kingdom of Barka Khan, after a year, their return blocked by war between Barka Khan and Hulagu Khan, the Polo brothers journey east to the capital Kaifeng and see Kublai Khan, three years later they returned to Venice
1267: China - Kublai Khan begins construction of new capital at Peking
1270-1270: Tunisia - French king Louis IX dies in Tunisia while on the Eighth Crusade (of nine), during his reign he Increased both the authority of the king and the judicial system
1271-1272: Egypt - Ninth Crusade (of nine), future Edward I of England undertook another expedition against Baibars/Baybars in 1271, after having accompanied Louis on the Eighth Crusade, the Ninth Crusade is a failure and ends the Crusades in the Middle East
1271: China - Kublai Khan formally creates the Yuan dynasty of China
1271: Italy, China - Marco Polo leaves for China with his father Niccolo, they arrive in the court of the Great Khan
1273: Italy - The last Emperor of the Holy Roman Empire dies and the Hapsburg Dynasty is established with the new Emperor Rudolf I of the Hapsburgs who five years later gain control over Austria, the Hapsburgs last until 1918
1274: Mongolia, Japan - Mongols unsuccessfully attempt to Invade Japan
1275: China - The Polos arrive at Cambuluc (Peking)
1279: Mongolia, China - Mongols under Kublai Khan defeat Sung dynasty of China
1280: China - Kublia Khan, grandson of Genghis Khan, founds the Yuan dynasty in China and makes Peking his capital, he is the first non-Chinese to rule China, his empire stretches from China to Arabia to eastern Europe and is the largest the world has ever known
1281: Japan, China - The waiting Japanese troops repel a Chinese at Hakozaki Bay then a typhoon (Kamikaze or "Divine Wind") destroys the Mongol fleet of Kublia Khan
1282: Danish - nobility forced Eric V to sign a Danish "Magna Carta" which establishes a Danish parliament
1284: Italy - Republic of Genoa defeats the rival Italian city state of Pisa in a naval battle off Meloria
1286: Mongolia, China - Nayan, uncle of Kublai Khan, with 400,000 horsemen, meets Kublai Khan, with 260,000 cavalry and 100,000 Infantry, in battle, Kublai Khan is victorious, and Nayan is captured and executed
1291: Israel - Moslems expel Crusaders from the Middle East
1291: Switzerland - Three Swiss cantons, Uri, Schwyz, and Unterwalden form the League of the Three Forest Cantons for mutual defense, this League constitutes the basis for the ultimate establishment of the Swiss state
1293: Sweden, Finland - Eric IX (Jedvardsson), Christian King of Sweden, defeats the Finns and forces them to convert to Christianity
1294: Mongolia - Kublai Khan dies
1295: Iran, Italy - Khans of Persia convert to Islam, the Polos return to Venice
1296: Italy - Marco Polo, fighting for Venice, is captured by Genoa and Imprisoned for two years, where he dictates his travels to his fellow Inmate, Rustichello da Pisa, who Incorporates tales of his own as well as other collected anecdotes and current affairs from China, the book is called "The Travels of Marco Polo", It depicts the journey throughout Asia, giving Europeans their first comprehensive look into the Inner workings of the Far East, Including China, India, and Japan
1298: China - Chinese develop a cannon
1298: England - Battle of Falkirk, English under Edward I defeat the Scots who had rebelled under the leadership of William Wallace
1302: Belgium, France - Battle of the Spurs, Flemish army defeats French army near Courtrai, Belgium
1302: France - Philip IV of France calls together representatives of the nobility, townspeople and clergy, the meeting became known as the Estates-General, the purpose is to garner support against Pope Boniface whose 'Unam Sanctum' proclaims Papal supremacy over national leaders
1309: France - Pope Clement V, heavily Influenced by Philip IV of France, takes residency in Avignon, France (until 1378)
1314: Scotland, England - Battle Bannockburn (central Scotland), the Scots, led by Robert the Bruce, routes a larger force led by Edward II, King of England and gains Scottish Independence for the next three centuries
1315-1317: Europe - The Great Famine occurs, the worst famine to strike northern Europe, It started with bad weather which caused crop failures for the next two years, It took until 1322 to fully recover and millions died
1315: Switzerland, Austria - Battle of Morgarten, Swiss forces, led by the canton of Schwyz, defeat Leopold I (Hapsburg), Duke of Austria and leads to an expanded Swiss alliance
1324: Mali, Saudi Arabia - Ruler of Mali makes pilgrimage to Mecca
1326: France, England - England is Invaded by the French wife of King Edward II, Isabelle, she is supported by French troops and gains control of England as Edward II was forced to flee London, Isabelle arranges for her son Edward III to be crowned King of England
1326: Turkey - Ottoman Empire is established when the Byzantine fortress of Bursa fall after a nine-year siege to the forces of the Osmali Turks, under Osman who soon dies and is succeeded by his son Orkhan who rules until 1360