While in power, the Angeloi were unable to stop the invasions of the Turks by the Sultanate of Rum, the uprising and resurrection of the Bulgarian Empire, and the loss of the Dalmatian coast and much of the Balkan areas won by Manuel I Komnenos to the Kingdom of Hungary.

It is said that he, "was accustomed to spending the greater part of the day in bed ... whenever the sun appeared, he would seek the darkness, like a wild beast; he took much pleasure in rubbing his decaying teeth, putting new ones in the place of those that had fallen out through old age.

[5] His efforts to contain the threat of "the barbarians" was twofold in nature – he assembled a force of 100 ships at the capital and brought in troops to strengthen the walls of Constantinople.

[5] Andronikos seems to have taken this lightly, as yet another tiresome rebellion to destroy – only when the palace guards refused to obey him did he realise the full extent of the danger.

Summoning up every soldier that could be spared in the vicinity, Isaac ordered Alexios Branas, his most able general, to drive back the Normans, who had lost all discipline and grown overconfident and fat in their anticipation of an easy victory at the capital.

Many answered the call and an army of some 200,000 in total participated – roughly 150,000 – 100,000 men were sent by the Holy Roman Empire alone, a natural rival of Byzantium to the Imperial claim.

However, his son and successor Richard I of England took the vow and along with his rival, Philip II of France took to the sea to retake the Holy Land.

All three of these Crusaders had some scores to settle with Byzantium – Richard was the brother-in-law of William II of Sicily through the marriage of the later with his sister Joan of England.

The odd exception came when Richard crushed the rebellion of Isaac Komnenos and refused to hand the island of Cyprus back to Byzantium, using it instead to tame his rebellious vassal Guy of Lusignan, former King of Jerusalem.

As he neared Byzantium, Stefan Nemanja of Serbia and the above-mentioned Peter IV of Bulgaria hastily concluded an anti-Byzantine alliance with the Holy Roman Emperor.

[8] Panicked by the sudden and overwhelming opponent army arriving, Isaac refused to offer Frederick support, imprisoning his envoys.

As it marched across the Anatolian peninsula, it encountered frequent Turkish raids, despite official gestures of friendship from the Sultanate of Rûm under Kilij Arslan II.

Frederick's army would later slowly but surely disband after the Holy Roman Emperor was found dead (presumed to have either drowned in a river, suffered a heart attack or perhaps both).

Meanwhile, the Third Crusade achieved ephemeral success – after a few indecisive victories against Saladin,[11] Richard was forced to depart for France where rumours reached him of planned treachery by his younger brother John, Lord of Ireland and of the intentions of his former ally Philip II, who had left the Crusade shortly after the Siege of Acre, to conquer the Duchy of Normandy.

In Easter of 1195, he wrote a stern letter to the Byzantine Emperor Isaac Angelos demanding a heavy tribute to pay for his mercenary troops.

It must be said however that the Byzantines after 1180 entertained no serious plans to reclaim Anatolia from the Turks, so how much territory Henry VI or his predecessor Frederick I seized may have been of little consequence in the long run.

[13] The Holy Roman Empire meanwhile was ravaged by civil war,[13] as Philip of Swabia and Otto of Brunswick had both been elected Kings of Germany by rival factions.

His older brother Henry II, Count of Champagne had already served as consort to Queen regnant Isabella I of Jerusalem, giving Theobald another prominent crusading relation.

Theobald proposed a new approach to the crusades: rather than an attack into the territory of the newly established Ayyubid dynasty, which was well defended after its recent defeat of the Seljuk Empire and surrounded by allied Islamic factions, a more fruitful effort could be directed against Egypt, now the centre of Muslim power in the Levant, but with most of its best troops campaigning in the East.

[13] Egypt would have given the Crusaders immense resources and shortened their supply lines; the local Christian population would also have reduced the major problem of manpower.

The crusade went badly from the start – Theobald died in 1201 and the army that arrived at Venice in the summer of 1202 was one third the size that had been anticipated (4,500 knights, 9,000 squires, 20,000 men-at-arms expected).

Venetian policy under the aging and blind but still ambitious Doge Enrico Dandolo was potentially at variance with that of the Pope and the crusaders because Venice was closely related commercially with Egypt.[15]).

Fortunately for Alexios IV, Phillip had good connections with the new leader of the Fourth Crusade, Boniface I of Montferrat (Theobald III, Count of Champagne had died in 1201).

[21] Alexios III Angelos, the Byzantine Emperor at the time made no preparations for the defence of the city – there were few troops and very few military vessels.

[19][22] However, the decisive actions of the Venetian Doge allowed him and his fellow countrymen to land on the beaches and before long the walls were in the hands of the Crusaders.

The Duke of Venice, an old man and stone-blind, stood on the prow of his galley with the banner of St. Mark and ordered his men to drive the ship ashore.

And when the others saw the standard of St Mark and the Doge's galley beached, they were ashamed and followed him ashore.Alexios IV soon began to realize that the generous offer promised to the Crusaders would not be met.

[26] Doukas was loosely related to the imperial family by having as his mistress Eudokia Angelina, daughter of Alexios III and Euphrosyne Doukaina Kamatera.

[12] Alexios V tried to rally a counter-attack but when this failed, he fled to Thrace with his mistress Eudokia Angelina and her mother Euphrosyne Doukaina Kamatera.

A common harlot was enthroned in the Patriarch's chair, to hurl insults at Jesus Christ; and she sang bawdy songs, and danced immodestly in the holy place...nor was there mercy shown to virtuous matrons, innocent maids or even virgins consecrated to God...When Innocent III heard of the conduct of his crusaders, he castigated them in no uncertain terms.