After their first spouses died, William and Sybil were married. What is unusualy about this is that both were ancestors in their first marriages but neither of their two children from their second marriage were ancestors.

William is a DOUBLE ancestor because he had a child with both his wives the each became an ancestor. Neither of his ancestral wives are double ancestors.

Historical
1353: Switzerland - Switzerland is established as a unified country
1356: England, France - Battle in Poitiers, the French defeat Black Prince of Wales Edward, the French king, John II, and his son, Philip the Bold of Burgundy, are taken prisoners at Poitiers, John is brought to England which results in civil chaos in France
1360: England, France - Treaty of Calias, England and France sign a treaty on October 24th, John II of France is ransomed and Edward III renounces his claim to the French throne
1364: Uzbekistan - Timur (Tamerlane) captures Samarkand (Uzbekistan)
1368: China - Chu Yuan-chang, a Han Chinese peasant and former Buddhist monk who had become a rebel army leader, emerged as successor to Kublai Khan, founding the Ming dynasty, with a capital at Nanking
1369: Netherlands - Amsterdam joins Hanseatic League
1371: Turkey, Bulgaria - Serbs defeated by Ottoman Turks at Maritsa River (Bulgaria)
1372-1375: England, France - Hundred Years War resumes when the French fleet defeats the British fleet off La Rochelle y France, the French are helped by a powerful fleet from Castile, the Truce of Bruges is signed on June 27, 1375 limiting British presence in France to Calia, Brest, Bordeaux and Bayonne
1381: England - The Peasants Revolt led by Wat Tyler create anarchy throughout England burning a number of public buildings and beheading the archbishop of Canterbury, King Richard puts down the riot and Tyler is killed
1381: Italy - War of Chioggia, Venetian fleet under Vittoria Pisano defeat the Genoans, It begins the golden age of Venice
1384: Uzbekistan - Timur captures Herat, Sistan, Rayy, and Il-Khanid (the capital of Sultaniyeh)
1385: Portugal - Battle of Aljubarrota (central Portugal), Portugese under King John I defeat the Crown of Castile under King John I and his allies, the victory makes Portugal an Independent country
1389: Turkey - Turkish army under Sultan Murad I defeats Serbs under Prince Lazar at Kossovo Field (meaning "field of the black birds"), bringing Turkish rule to the area which lasts until the Balkan War of 1913, just before the battle, a Serb posing as a deserter brought before Sultan Murad produces a dagger and stabs the Sultan to death, he is Immediately killed, as is Serb leader Lazar who is captured in the battle
1392: China - Yi Songgye, with the aid of the Ming rulers of China, seize the Korean throne from the Koryo dynasty, the Yi dynasty lasts until 1910
1395: Mongolia - Timur sacks Sarai Berke, ending central control of the Mongol Golden Horde
1396: Turkey, Hungary - Ottomans defeat Hungarians at Nicopol
1397: Sweden, Norway, Denmark - Magaret, Queen of Sweden, conquers Denmark and Norway then forms the Kalamar League, a union of all three countries
1398: Mongolia, India - Timur sacks Delhi, causing demise of the Delhi Sultinate, founded back in 1192
1400: Indonesia - Paramesvara founds the Kingdom of Malacca on the Malay peninsular (Indonesia), It soon becomes the leading maritime power in South East Asia
1400: Mongolia, Syria, Russia, Georgia, Iraq - Mongol conqueror Timur Invades Syria after devastating Georgia and Russia, the next year he lays waste to Aleppo, Damascus and Baghdad and the year after that e defeats the Ottoman sultan at the Battle of Angora
1402: Mongolia, Turkey - Timur captures Ottoman Turk Sultan Beyazid I at Angora
1405: Mongolia - Mongol leader Timur dies suddenly while preparing to attack Ming China, the Mongol Empire rapidly falls apart, Timur is buried at Samarkand (Uzbekistan)
1410: Poland, Germany - Battle of Tannenberg, Poles and Lithuanians defeat German Knights, the Peace of Thorn is signed but the Poles failed to gain access to the sea
1412: France - Joan of Arc born in Domremy, France
1415: England, France - Henry V of England defeats French army at Agincourt, Pas de Calais, France, 7,000 French killed, 500 English killed
1415: England - Battle of Agincourt, the English destroy the French, British archers under the command of Henry V were the key to victory, shattering the feudal system
1415: Portugal, Morroco - Portuguese explorer and prince, Henry the Navigator captures Ceuta (Morocco) from the Marind dynasty beginning Portuguese colonization of Africa
1420: China - Upon the death of the Ming emperor, the sSecond Ming Emperor moves the capital of China from Nanking to Peking
1420: England, France - Treaty of Troyes, France (under Philippe) signs a treaty with England (under Henry V) making Henry the king of both countries