On This Day: April 9th

Resettled Shiite Muslims rise up in the Şahkulu rebellion under the leadership of Şahkulu against the Ottoman Empire.

The Treaty of Lodi is signed, establishing a balance of power among northern Italian city-states for almost 50 years.

The Council of Ferrara begins with its first session in presence of the Patriarch of Constantinople, representatives of the Patriarchal Sees of Antioch, Alexandria and Jerusalem and Pope Eugene IV presiding.

Despite being outnumbered 16:1, forces of the Old Swiss Confederacy are victorious over the Archduchy of Austria in the Battle of Näfels.

The Byzantine city of Thessalonike surrenders to the Ottomans, though rule reverts back to the Byzantines after the battle of Ankara.

Mongol invasions of Vietnam: Yuan forces are defeated by Trần forces in the Battle of Bach Dang in present-day northern Vietnam.

Battle of Liegnitz: Mongol forces defeat the Polish and German armies.

Siege of Rome: The Byzantine general Belisarius receives his promised reinforcements, 1,600 cavalry, mostly of Hunnic or Slavic origin and expert bowmen. Despite shortages, he starts raids against the Gothic camps and Vitiges but is forced into a stalemate.

Byzantine Emperor Basiliscus issues a circular letter (Enkyklikon) to the bishops of his empire, supporting the Monophysite christological position.

The distinguished soldier Septimius Severus is proclaimed emperor by the army in Illyricum.