In April 1204 the army of the Fourth Crusade stormed Constantinople and sacked it for three days, the first time in nine centuries the city had been taken by an enemy.
Constantinople had been besieged by Avars, Persians, Arabs, Bulgars, Rus and Vikings across nine centuries, and had never fallen. In April 1204 it was taken by an army of western Christians who had set out to attack Egypt.
The crusade had come to Constantinople the previous year to install Alexios IV, who had promised it enormous sums. He could not deliver, was deposed and strangled in January 1204, and his successor Alexios V repudiated the debt entirely.
The crusaders and the Venetians then agreed among themselves — in a treaty signed in March, before the assault — to take the city and divide the empire. They stormed the sea walls on 12 April and sacked the city for three days.
The attack came from the Golden Horn rather than the land walls, which is the tactical fact that decided it. The Theodosian land walls had never been forced; the sea walls were lower, and the Venetian fleet could bring ships directly against them.
The first assault, on 9 April, failed. The ships could not hold position against the wind and current and the troops that landed were driven off. The second, on 12 April, lashed ships together in pairs to steady the flying bridges, and a handful of men got onto the towers.
Once a section of wall was carried the defence collapsed with startling speed. Alexios V fled the city that night. The Varangian Guard, who were paid professionals and had fought properly throughout, negotiated. By the following morning the city was open.
The sack lasted three days and was, by the standards even of its own century, exceptional — and it is worth being careful here, because the account is not only Greek. Villehardouin and Robert of Clari, both participants, describe plunder on a scale they found remarkable, and Pope Innocent III condemned it in the strongest terms available to him.
The bronze horses that stand at San Marco in Venice came from the Hippodrome. The Pala d'Oro was enriched with Constantinopolitan enamels. Relics went west in enormous numbers and are traceable in French and Italian church inventories for centuries afterwards. Niketas Choniates, who was there and lost everything, describes soldiers drinking from altar vessels in Hagia Sophia and a prostitute seated on the patriarch's throne — a scene written to shock and probably not invented.
The bronze statuary of the Hippodrome and the fora, which included antique work that had survived a thousand years, was melted down for coin. That is the loss that cannot be recovered or repatriated, and the one the archive would single out: much of what the classical world had left standing in one place ended in 1204 as small change.
The Partitio Romaniae had been drafted before the walls were carried. Baldwin of Flanders was elected Latin emperor; Boniface of Montferrat, who had expected it, took Thessalonica instead; and Venice took three-eighths of the empire, choosing harbours, islands and the approaches to the Black Sea rather than land.
That choice made Venice the dominant commercial power of the eastern Mediterranean for three hundred years and is the clearest single beneficiary of the whole affair.
The Greek response was to reconstitute the empire in three places at once — Nicaea, Epirus and Trebizond — each claiming the imperial title. The archive follows that fight through Pelagonia in 1259 to the recovery of the city in 1261.
The empire restored in 1261 was a different order of thing: a regional power with a fraction of its territory, no fleet, an economy in the hands of Italian merchants it could not tax, and a permanent Turkish frontier in Anatolia it could no longer push back.
The damage to relations between the Greek and Latin churches outlived every political consequence. The schism of 1054 had been an argument among clergy; after 1204 it was something the population of a great city had personal cause to hold, and the later attempts at union — Lyon in 1274, Florence in 1439 — foundered on that as much as on theology.
When the Ottomans took the city in 1453 they took a place that had been sacked once already, by its allies, and had never fully recovered. It is difficult to read the two events apart.