On This Day: April 1

Emperor Diocletian elevates his general Maximian to co-emperor with the rank of Augustus and gives him control over the Western regions of the Roman Empire.

Crown Prince Jin Chengdi, age 4, succeeds his father Jin Mingdi as emperor of the Eastern Jin dynasty.

Majorian is acclaimed emperor by the Roman army after defeating 900 Alemanni near Lake Maggiore (Italy).

Byzantine Emperor Justin I names his nephew Justinian I as co-ruler and successor to the throne.

The daughter of Emperor Xiaoming of Northern Wei was made the "Emperor" as a male heir of the late emperor by Empress Dowager Hu, deposed and replaced by Yuan Zhao the next day; she was the first female monarch in the History of China, but not widely recognised.

Robert Winchelsey leaves England for Rome, to be consecrated as Archbishop of Canterbury.

Berwick-upon-Tweed is captured by Scotland from England.

Niels Ebbesen kills Gerhard III, Count of Holstein-Rendsburg in his bedroom, ending the 1332-1340 interregnum in Denmark.

Potosí is founded after the discovery of huge silver deposits in the area.

In the Eighty Years' War, the Watergeuzen capture Brielle from the Seventeen Provinces, gaining the first foothold on land for what would become the Dutch Republic.