War of the Three Henries (976–978)

However, like his father he had to cope with a restless Saxon nobility, hostile towards his "foreign" consort, Theophanu, and the unstable conditions in Italy culminating in the murder of Pope Benedict VI in 974.

Temporarily imprisoned in Ingelheim, Duke Henry returned to Bavaria in 976 and continued to plot against Otto, even scheming with Saxon nobles like Gunther, Margrave of Merseburg, Egbert the One-Eyed or Dedo I of Wettin.

Otto marched against Bavaria and occupied Henry's residence in Regensburg; the duke had to flee to the court of his ally Boleslaus II of Bohemia.

He enfeoffed his nephew Otto I, Duke of Swabia since 973, with remaining Bavaria and vested the Luitpolding scion Henry the Younger with the newly established Duchy of Carinthia.

In September Otto counter-invaded the West Frankish kingdom, capturing Reims, Soissons, Laon and laying siege to Paris.