A copper shortage during the reign of…

Michael recognizes Charles's title of Western Roman Emperor in return for the cession to Constantinople of Venice and other cities on the Adriatic.

The new emperor is unable to deal with the Bulgarians immediately because of an Iconoclast revolt that aims to replace him with a son of the former emperor Constantine V. After Michael has suppressed the insurrection, Krum offers to conclude peace, but the terms offered seem unacceptable to Theodore Studites, and on his advice, Michael declines the proposal.

Krum next captures the imperial fortress of Develtus, an important customs and border control point, and transports its inhabitants to Bulgaria.

Norse invaders in 812 settle Limerick, situated on the estuary of the River Shannon, in west central Ireland.

Krum now renews hostilities, capturing the city of Mesembria in November 812.

The Discovery of Saint James' Remains and the Rise of Santiago de Compostela (813 CE)

According to tradition, in 813 CE, the alleged remains of the apostle James (Saint James the Great) are discovered in Galicia.

Seizing the religious and political significance of this event, King Alfonso II of Asturias orders the construction of a church on the site, enhancing the prestige of his kingdom. The site soon becomes a center of pilgrimage, attracting devout travelers from across Christendom.

Over time, the city of Santiago de Compostela develops around the shrine, eventually becoming one of the most important pilgrimage destinations in medieval Europe, second only to Jerusalem and Rome, and laying the foundation for the Camino de Santiago (Way of Saint James).

Louis the Pious is one of the three legitimate sons of Charles I, including his twin brother, Lothair, to have survived infancy.

According to Frankish custom, Louis had expected to share his inheritance with his brothers, Charles the Younger, King of Neustria, and Pepin, King of Italy.

In the Divisio Regnorum of 806, Charles had slated Charles the Younger as his successor as emperor and chief king, ruling over the Frankish heartland of Neustria and Austrasia, while giving Pepin the Iron Crown of Lombardy, which Charles possesses by conquest.

To Louis's kingdom of Aquitaine, he has added Septimania, Provence, and part of Burgundy, but in the event, Charles's other legitimate sons have died—Pepin in 810 and Charles in 811—and Louis alone remains to be crowned co-emperor with Charles in 813.

The general Leo, called the Armenian, had at first joined Bardanes Turcus but later sided with Nikephoros when the two were fighting over the imperial throne in 803.

Distinguishing himself as a general under Nikephoros and Michael, Leo has become strategos (“general”) of the Anatolikon district of the empire.

Michael defeats the Bulgarians in several engagements in which Leo takes part, but on June 22, 813, the emperor loses the Battle of Versinikia near Adrianople.

Krum seizes Adrianople and moves some fifty thousand captives to the Bulgarian lands towards the north of the Danube.

When Michael unwisely refuses the peace terms the Bulgarians offer, the Asian troops under Leo desert.

Leo then deposes Michael and …

…replaces him as Leo V in July.

Michael retires to a monastery on one of the Princes Islands.

The way opened for further Bulgar victories, Krum besieges Constantinople in 813 and devastates the surrounding countryside.

Harthama ibn A'yan had been in Samarkand when al-Rashid died at Tus in March 809, and remained in the east after.

Consequently he had thrown in his lot with al-Ma'mun in the civil war against al-Amin, and is along with Tahir ibn Husayn one of the two commanders of al-Ma'mun's army during the crucial year-long siege of Baghdad.

During the siege Harthama leads the attack from the east while Tahir commands from the west.

In the final stage of the siege, Harthama tries unsuccessfully to secure the surrender and life of al-Amin, who has in the meantime been declared deposed as caliph in Iraq and Arabia, by sending a boat to ferry him over the Tigris.

The boat, however, capsizes, and al-Amin is captured and executed by Tahir's men, contrary, it seems, to al-Ma'mun's orders, on September 24 or 25, 813.

The father of Hassan ibn Sahl was an Iranian Zoroastrian convert to Islam.

Along with his brother, the future vizier al-Fadl ibn Sahl, Hasan had entered the service of the Barmakid al-Fadl ibn Yahya in the reign of Harun.

During the civil war, he has been entrusted with the supervision of the land tax (kharaj) office.

After Ma'mun's troops capture the caliphal capital, Baghdad, Hasan is sent west to assume the governance of Iraq, while Ma'mun and Fadl remain in Marv.

Al-Ma'mun rules from 813 as the recognized caliph, but Egypt, Syria, and Mesopotamia begin to slip from central control.

Halfdan the Mild may have won independence for Vestfold during the turbulent years of 813–14, according to the historian Halvdan Koh.

The Frankish annals state that the kings of Hedeby had to solve an uprising in Vestfold at this time.

Halfdan’s people, according to Ynglingatal, "gained victory" in this uprising, and Halfdan is thus the first independent ruler of Vestfold.