Editing Fourth Crusade (section)

=== Siege of July 1203 ===
{{Main|Siege of Constantinople (1203)}}
[[File:Crusaders attack Constantinople.jpg|thumb|right|upright=1.15|The Crusader attack on Constantinople, from a Venetian manuscript of Geoffrey de Villehardouin's history, {{circa|1330}}]]
To take the city by force, the crusaders first needed to cross the [[Bosphorus]]. About 200 ships, horse transports, and [[galley]]s delivered the crusading army across the narrow strait, where Alexios III had lined up the Byzantine army in battle formation along the shore, north of the suburb of Galata. The Crusader knights charged straight out of the horse transports, and the Byzantine army fled south. The Crusaders followed and attacked the [[Galata Tower (old)|Tower of Galata]], which held the northern end of the massive chain that blocked access to the [[Golden Horn]]. The Tower of Galata held a garrison of mercenary troops of English, Danish, and Italian origin.<ref>{{cite book |last1=Andrea |first1=Alfred |title=Contemporary Sources For The Fourth Crusade |pages=191–192}}</ref> On 6 July the largest ship in the crusaders' fleet, the ''Aquila'' (Eagle), broke the chain. A section of it was then sent to Acre to boost the defences in the Holy Land.<ref name=Kedar />

As the crusaders laid siege to the Tower of Galata, the defenders routinely attempted to sally out with some limited success, but often suffered bloody losses. On one occasion the defenders sallied out but were unable to retreat back to the safety of the tower in time, the Crusader forces viciously counterattacked, with most of the defenders being cut down or drowning in the Bosporus in their attempts to escape.<ref>{{cite book |last1=Andrea |first1=Alfred |title=Contemporary Sources For The Fourth Crusade |page=193}}</ref> The tower was swiftly taken as a result. The Golden Horn now lay open to the Crusaders, and the Venetian fleet entered. The Crusaders sailed alongside Constantinople with 10 galleys to display the would-be Alexios IV, but from the [[walls of Constantinople|walls of the city]] citizens taunted the puzzled crusaders, who had been led to believe that they would rise up to welcome the young pretender Alexios as a liberator.{{sfn|Phillips|2004|p=164}}

On 11 July, the Crusaders took positions opposite the [[Palace of Blachernae]] on the northwest corner of the city. Their first attacks were repulsed, but on 17 July, with four divisions attacking the land walls while the Venetian fleet attacked the sea walls from the Golden Horn, the Venetians took a section of the wall of about 25 towers, while the Varangian guard held off the Crusaders on the land wall. The Varangians shifted to meet the new threat, and the Venetians retreated under the screen of fire. The fire destroyed about {{convert|120|acre|km2}} of the city and left some 20,000 people homeless.{{sfn|Phillips|2004|p=176}}

Alexios III finally took offensive action, leading 17 divisions from the St. Romanus Gate, vastly outnumbering the crusaders. Alexios III's army of about 8,500 men faced the Crusaders' seven divisions (about 3,500 men), but his courage failed, and the Byzantine army returned to the city without a fight.{{sfn|Phillips|2004|p=177}} The unforced retreat and the effects of the fire greatly damaged morale, and the disgraced Alexios III abandoned his subjects, slipping out of the city and fleeing to [[Mosynopolis]] in [[Thrace]].<ref name="Runciman100">Runciman, Steven. ''The Kingdom of Acre and the later Crusades'', (1954; repr., London: Folio Society, 1994), 100</ref> The Imperial officials quickly deposed their runaway emperor and restored Isaac II, robbing the crusaders of the pretext for attack.<ref name="Runciman100" /> The crusaders were now in the quandary of having achieved their stated aim while being debarred from the actual objective, namely the reward that the younger Alexios had (unbeknownst to the Romans) promised them. The crusaders insisted that they would only recognize the authority of Isaac II if his son was raised to co-emperor, and on 1 August the latter was crowned as Alexios Angelos IV, co-emperor.<ref name="Runciman100" />