The imprisoned Emperor Go-Daigo escapes from the capital in 1337, the Sacred Treasures that he had handed over to the Ashikaga being counterfeit, and sets up the Southern Court among the mountains of Yoshino, beginning the Period of Northern and Southern Courts in which the Northern Dynasty in Kyōto and the Southern Dynasty in Yoshino face off against each other.

Go-Daigo orders Imperial Prince Kaneyoshi to Kyūshū and Nitta Yoshisada and Imperial Prince Tsuneyoshi to Hokuriku, and so forth, dispatching his sons all over, so that they can oppose the Northern Court.

Emperor Musa Keita I of Mali, famous in North Africa and Europe as the monarch who controls the world's richest gold mines, has also established cordial relations with Muslim rulers in North Africa and become noted for his efforts to spread Islam among his subjects.

The emperor has made his capital, Timbuktu, a great center of commerce and learning, and established internal peace and prosperity.

Mansa Musa dies in 1337; his son, Magha, succeeds him.

Philip VI Declares War on Edward III: The Beginning of the Hundred Years’ War (1337)

By 1337, tensions between Philip VI of France and Edward III of England had reached a breaking point. The immediate cause was Philip’s decision to confiscate the Duchy of Aquitaine (Gascony), triggering the Hundred Years’ War (1337–1453).

Philip VI’s Refusal to Negotiate (April 1337)

• Philip was invited to meet with an English delegation at the end of April 1337, but he refused, signaling that diplomatic efforts had collapsed.
• On April 30, 1337, the arrière-ban, or royal call to arms, was proclaimed throughout France, preparing the kingdom for war against England.

Philip’s Great Council and the Confiscation of Aquitaine (May 1337)

• In May 1337, Philip VI convened his Great Council in Paris to discuss the worsening crisis with England.
• The council unanimously agreed that the Duchy of Aquitaine (effectively Gascony) should be seized.
• Philip justified this move by accusing Edward III of violating his feudal obligations as vassal and for providing shelter to the king’s "mortal enemy," Robert III of Artois.

The Final Break and the Road to War

• By taking Gascony into his own hands, Philip VI directly challenged English sovereignty over its last remaining continental possession.
• Edward III saw this as a clear act of aggression, and by autumn 1337, he had begun preparing for war against France.
• In October 1337, Edward formally revoked his homage to Philip VI, effectively declaring himself independent of French suzerainty.

The Start of the Hundred Years’ War

• The confiscation of Aquitaine in 1337 marked the beginning of open hostilities between England and France, leading to one of the longest and most consequential wars in medieval Europe.
• Though rooted in feudal disputes, the conflict evolved into a struggle for the French crown, particularly after Edward III formally claimed the French throne in 1340.

Philip VI’s decision in 1337 to seize Gascony was the final act that pushed England and France into full-scale war, ushering in a new era of military and political conflict that would last for more than a century.

Edward III creates the first nonruling duke in England by making his oldest son, Edwar of Woodstock, Duke of Cornwall in 1337.

Rebel leader Ashikaga Takauji takes control of the capital and sets up a puppet emperor who reciprocates by appointing Takauji shogun in 1338.

Takauji rules from the Muromachi district of Kyoto, relying on Zen monks as intermediaries in foreign relations.

By so doing, Andronikos and Kantakouzenos are able to call on the services of almost limitless numbers of Turkish soldiers to fight for them against their other enemies: the Italians in the Aegean islands and the Serbs and the Bulgars in Macedonia and Thrace.

The Ottomans have by 1338 conquered most of western Asia Minor, and Emperor Andronikos III has reluctantly acquiesced to Orhan’s terms of truce, as he requires Turkish help against the expansionist Serbs under Stephen Dushan.

Northwestern Anatolia, once the heart of the empire, is lost to Greek rule after the Turkish warriors of Orhan, second emir of the powerful Ottoman principality, had captured Nicomedia in 1337, renaming it Izmit, …

… Chrysopolis.

Taddeo Gaddi, the son of Gaddo di Zanobi, called Gaddo Gaddi, had been a member of Giotto's workshop from 1313 to 1337, when his master died.

His principal work is the cycle of Stories of the Virgin in the Baroncelli Chapel of the Basilica of Santa Croce in Florence (1328–1338).

Later he perhaps paints the cabinet tiles in the sacristy of the same church, now divided among the Galleria dell'Accademia of Florence and museums in Munich and Berlin.

These works show his mastership of Giotto's new style, to which he has added a personal experimentation in the architectural backgrounds, such as in the staircase of the Presentation of the Virgin in the Baroncelli Chapel.