[9] In 1195, Richard began negotiations to marry Otto to Margaret, daughter and heir presumptive of King William the Lion of Scotland.

[10][9][11] Lothian, as Margaret's dowry, would be handed over to Richard for safekeeping and the counties of Northumberland and Cumberland (Carlisle) would be granted to Otto and turned over to the king of Scotland.

[6] Otto was in Poitou from September 1196 until mid-1197, when he joined Richard in Normandy to confer over the appointment of bishops to the vacant sees of Poitiers, Limoges and Périgueux.

[15] The papacy meanwhile, under Innocent III, determined to prevent the continued unification of Sicily and the Holy Roman Empire under one monarch[16] seized the opportunity to extend its influence.

The confusion in the empire allowed Innocent to drive out the imperial feudal lords from Ancona, Spoleto, and Perugia, who had been installed by Emperor Henry VI.

Philip achieved a great deal of success in the civil war that followed, allowing him in 1204 to be again crowned king, this time by the archbishop of Cologne.

Otto was defeated and wounded in battle by Philip on 27 July 1206, near Wassenberg, and as a consequence, he also lost the support of the pope, who began to favour the apparent winner in the conflict.

[citation needed] Otto was forced to retire to his possessions near Brunswick, leaving Philip virtually uncontested as German king.

[19] Innocent III forced the two warring parties into negotiations at Cologne, and in exchange for renouncing his claim to the throne, Philip promised Otto the hand of his daughter Beatrix in marriage, together with the Duchy of Swabia and an enormous dowry.

To secure Innocent's support, he promised to restore to the Papal States all territory that it had possessed under Louis the Pious, including the March of Ancona, the Duchy of Spoleto, the former Exarchate of Ravenna, and the Pentapolis.

[20] Travelling down via Verona, Modena, and Bologna, he eventually arrived at Milan, where he received the Iron Crown of Lombardy and the title of King of Italy in 1208.

[22] Not content with his successes so far, Innocent also obtained from Otto further written concessions to the Papal See,[citation needed] including allowing all elections of German bishops to be conducted according to Church ordinances and not to prevent any appeals to Rome.

[24] After his consecration by the pope, he promised to restore the lands bequeathed to the church by the countess Matilda of Tuscany nearly a century before and not to move against Frederick, King of Sicily.

He commanded Innocent to annul the Concordat of Worms and to recognise the imperial crown's right to make nominations to all vacant benefices.

[27] Although he claimed he had repented for his offences and declared his willingness to be obedient to the Pope in all things, Innocent III had already recognised Frederick as emperor-elect.

[29] He found most of the German princes and bishops had turned against him and that Frederick, who had made his way up the Italian peninsula, had avoided Otto's men who were guarding the passes through the Alps and had arrived at Constance.

[31] The support that Philip II of France gave to Frederick forced King John of England to throw his weight behind his nephew, Otto.

It was not until John, who had been disappointed in his hope for an easy victory after being driven from Roche-au-Moine, had retreated to his transports that the Imperial Army, with Otto at its head, assembled in the Low Countries.

[35] His cause of death is disputed, with some claims that he died of disease at Harzburg castle on 19 May 1218, requesting that he be mortally expiated in the atonement of his sins.