| Conflict: | Byzantine–Venetian War of 1171 |
| Date: | 1171–1172 |
| Place: | Aegean Sea |
| Result: | Byzantine victory |
| Combatant1: | Republic of Venice |
| Combatant2: | Byzantine Empire |
| Commander1: | Doge Michiel Enrico Dandolo Filippo Greco |
| Commander2: | Manuel I |
| Strength1: | 100 Galleys 20 Transports |
| Strength2: | 150 ships |
| Casualties1: | Most of the fleet |
The Byzantine–Venetian War of 1171 was fought between the Byzantine Empire and the Republic of Venice as a result of the Byzantine imprisonment of Venetian merchants and citizens across the Empire. 10,000 Venetians were imprisoned in the Byzantine capital, Constantinople, alone. Despite Doge Michiel's apparent will to pursue a peaceful solution, outrage in Venice itself swung popular opinion in the favour of full scale war against Byzantium. Doge Michiel had no choice but to set out for war, which he did in mid-late 1171.[1]
The disastrous defeat of Venice in this war was one of the greatest military blunders in the city-state's history, and permanently altered Venice's position on foreign affairs. A formal truce between the two empires would not be ratified until 1177, with minor skirmishes continuing until then.[6]