The 12th-century military disaster that forever changed global finance View our Twitter (X) feedView our Youtube channelView our Instagram feedView our Substack feedView our Spotify feed The 12th-century military disaster that forever changed global finance After a plague-ridden crusade left Venice drowning in debt, the republic created the world's first bond market, changing the relationship between the government and its citizens. History and SocietyMedieval HistorySocial MobilityFinancial MarketsCivic Institutions Excerpted from A Fabulous Debt: The Epic Story of How Bonds Built the Modern World by Robin Wigglesworth, in agreement with Portfolio, an imprint of Penguin Publishing Group, a division of Penguin Random House LLC. Copyright © Robin Wigglesworth, 2026.
The birth of the bond market started with a ruthless multinational raid that sent shock waves through the Mediterranean. On the morning of March 12, 1171, the Byzantine emperor’s soldiers suddenly rounded up every Venetian man, woman, and child they could find throughout their lands, seized their shops, wares, and ships, and threw the owners in jail. Over 10,000 people in Constantinople alone were rounded up, and more than 20,000 overall — so many that monasteries were requisitioned to handle the overflow.
The raids were a consequence of more than a century of rising tensions between Constantinople and its nominal vassal in northern Italy. By the 12th century, Venice was the beating heart of Mediterranean trade. It became Europe’s emporium, with 80,000 citizens almost all dedicated to commerce in some fashion.
Partnership contracts between investors and merchants known as _colleganza_ allowed even poorer citizens to pool their money, invest in long-distance trade, and share in both the risks and the spoils. These became known as _commenda_ elsewhere in Italy and were an early precursor to joint-stock companies that sprang up in northern Europe centuries later. These ensured a stunning level of social mobility in Venice.
One surviving _colleganza_ from the period reveals how Zaccaria Stagnario, the grandson of a freed Croatian slave and the son of a humble helmsman, managed to turn his skill as an entrepreneurial trader into a fortune, and eventually his family’s entry into the Venetian governing elite. As a result, anyone visiting the city’s Rialto market would have been astonished at the exotic products available at its multitude of shops and stalls, ranging from strong Bohemian iron and solid French oak to intricate jewelry from Antwerp, subtle Portuguese wines, pungent Levantine spices, Russian ermine, and religious relics brought back by returning Crusaders. Even centuries later, the Rialto was so famous that it was name-checked in Shakespeare’s _The Merchant of Venice_.
A zeal for trade had transformed Venice into one of the world’s wealthiest cities — something that Venice’s leader, Doge Vitale II Michiel, had to take advantage of in the hostilities with his suzerain in Constantinople. When news arrived of Emperor Manuel I Komnenos’s sweeping raids, the shocked doge summoned his counselors from Venice’s most prominent families to advise on a course of action. Together they agreed on caution, skeptical that the excitable reports they had received could be true and wary of how outright war would damage their main objective, commerce.
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