http://www.meetdubrovnik.com/en/dubr...-republic.html

Dubrovnik issued a decree on the abolition of slavery and the ban on the transport of slaves on its ships on January 27th in 1416. It was the first republic that banned slavery in Europe. In the 15th century, there were about 40,000 inhabitants, which made it one of the major cities in Europe (London, about 50,000, Florence over 100,000).

In Dubrovnik, freedom was the most respected. It had its own flag (with the image of the patron Saint Blaise and the other with the letters "LIBERTAS - Lat. Freedom"), and it could be seen on military coats. Dubrovnik connected the diplomatic and representative offices in many European countries. Their interests in the courts of European monarchs represent the envoys, while protecting the interests of the consulates in Dubrovnik sailors in the same time.