Atlas of Battles

siege, major, medieval

Siege of Constantinople

Siege of Constantinople was a siege conducted on 1 August 1203 at Constantinople, in what is now Turkey. It was part of the Fourth Crusade, which ran from 1202 to 1204. The recorded result: Crusader victory; Alexios IV Angelos takes Byzantine throne. Recorded strength: Crusaders: 10,000 men; Venetians: 10,000 men and 210 ships against 15,000 men and 20 ships.

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Topographical map of Constantinople during the Byzantine period.
Topographical map of Constantinople during the Byzantine period.. Cplakidas, CC BY-SA 3.0, via Wikimedia Commons.
Fought1 August 1203
WhereConstantinople, Turkey41.017N, 28.977E
OutcomeCrusader victory; Alexios IV Angelos takes Byzantine throne
BelligerentsFourth Crusade; loyalist of Alexios IV AngelosagainstByzantine Empire
Part ofFourth Crusade1202 to 1204

Record

Date1 August 1203
to 1 August 1203
PlaceConstantinople, Turkey
41.017N, 28.977E
KindSiege, medieval
StrengthCrusaders: 10,000 men; Venetians: 10,000 men and 210 ships15,000 men and 20 ships
Commanders
  • Alexios III Angelos
Siege of ConstantinopleSiege of ConstantinopleReconquest of ConstantinopleSiege of ConstantinopleSiege of ConstantinopleSiege of ConstantinopleSiege of ConstantinopleReconquest of ConstantinopleBursaAdapazarıTekirdağLüleburgazKırklareliBilecik100 km41.017N, 28.977E
The recorded site, with the nearest other engagements in the atlas. Present-day coastlines, rivers and borders; towns from Natural Earth.

The ground today

Relief of the ground around the site of Siege of Constantinople
Relief within about 10.0 km of the site, contours every 10 m. Copernicus DEM GLO-30, ESA.
Satellite view of the site of Siege of Constantinople today
The same ground from Sentinel-2 on 2025-07-22. Contains modified Copernicus Sentinel data 2025.

The recorded site stands at about 2 m; within 10.0 km the ground runs from -14 to 137 m, 151 m of relief, hilly country and today it is 50% water, 42% built-up, 5% tree cover.

water: 50%built-up: 42%tree cover: 5%water 50%built-up 42%tree cover 5%
west to east, 10.0 km0 to 66 mnorth to south, 10.0 km0 to 99 m
Elevation from the Copernicus DEM GLO-30 (ESA, Airbus); land cover from ESA WorldCover 2021 (CC BY 4.0), within about 5 km of the recorded site. Computed, not recorded.

Nearest engagements

Contested ground: this site was fought over 43 times between 510 BC and 1453.

In the same war

Elsewhere in 1203

Siege of Constantinople is one of 590 engagements of the 13th century in the atlas and one of 622 in present-day Turkey.

Sources

Identity, coordinates, dates and the war from Wikidata Q767844, released under CC0. Result, belligerents, commanders, strength and casualties from the infobox of the English Wikipedia article Siege of Constantinople (1203), revision 1380326576, read 2026-11-14, licensed CC BY-SA 4.0; the article's text is not reproduced here. Present-day country and state from Natural Earth. Dates before 1582 follow the Julian calendar as recorded.