The second, reigning son of cloistered Japanese emperor Toba, dies in 1155; Toba replaces him with a third son, who rules as Shirakawa II.

Yuri regains Kiev once again in 1155.

Disorder is again rampant in Germany, especially in Bavaria, but general peace is restored by Frederick's vigorous, but conciliatory, measures.

The duchy of Bavaria is transferred from Henry II Jasomirgott, margrave of Austria, to Frederick's formidable younger cousin Henry the Lion, Duke of Saxony, of the House of Welf, whose father had previously held both duchies.

Henry is named duke of Austria in compensation for his loss of Bavaria.

As part of his general policy of concessions of formal power to the German princes and ending the civil wars within the kingdom, Frederick further appeases Henry by issuing him with the Privilegium Minus, granting him unprecented entitlements as Duke of Austria.

The Seljuq state of Rukn ad-Din Mas'ud has, by the time of his death in 1155, become the dominant power in central and eastern Anatolia.

Pope Adrian IV swiftly takes steps to regain control of Rome, and endeavors to bring down Arnold of Brescia, the leader of the anti-papal faction in the city.

Disorder within the city leads to the murder of a cardinal, causing the Pope, shortly before Palm Sunday 1155, to take the previously unheard-of step of putting Rome under interdict.

He allies with Emperor Frederick Barbarossa, who takes Rome by force in 1155 after a Holy Week interdict and forces Arnold again into exile.

Arnold is seized by Imperial forces and tried by the Roman Curia as a rebel.

Importantly, he is never accused of heresy.

Faced with the stake, he refuses to recant any of his positions.

Convicted of rebellion, Arnold is hanged in June and his body burnt.

Because he remains a hero to large sections of the Roman people and the minor clergy, his ashes are cast into the Tiber, to prevent his burial place becoming venerated as the shrine of a martyr.

Frederick, crowned Holy Roman Emperor in Rome by Pope Adrian IV, leaves Italy in the autumn of 1155 to prepare for a new and more formidable campaign.

Adrian IV during his reign issues a papal bull, Laudabiliter, granting dominion over Ireland to the English monarch, Henry II.

The bull makes Ireland a feudal possession of the King of England under the nominal overlordship of the papacy.

The title the English King is to hold over Ireland is "Lord of Ireland".

The theory of western Christendom is that certain states are recognized and others are not; Laudabiliter formally brings Ireland as a political entity into the European polity.

Maio is not popular with the baronage and supports the immigration of Western Europeans, Roman Catholics all, to increase the influence of this church, which is initially his largest supporter.

The chief baronial opponent to Maio is, at first, Robert de Bassonville, the count of Loritello and cousin to the king.

He resents Maio's rise and his own cousin helps the imperial forces to recover Bari, …

…Trani, …

…Giovinazzo, …

…Andria, …

…and Taranto by the end of 1155, and to …