In April 1397 a fire desolated Wervik, a city in Flanders with a large successful textile industry, whose clothes (known collectively in Italy as ‘panni di Vervi’) were exported as far afield as the Muslim world. The fire destroyed more than 800 houses made of wood and straw, causing the loss of part and fully manufactured clothes. Some Florentine merchants were operating in the city as representatives of their company based in Bruges. These included the brothers Diamante and Altobianco degli Alberti, who suffered large losses in the disaster. The fire hit Florentine merchants, and their business network extending across Europe and the Mediterranean area, hard. This paper examines commercial correspondence and accounting records to focus on the impact that this fire had on Florentine business structures, including perceptions and descriptions of the event and its immediate and long-term consequences.