Pietro II Orseolo

Pietro II Orseolo (961−1009) was the Doge of Venice from 991 to 1009, and a member of the House of Orseolo. He began the period of eastern expansion of Venice that lasted for the better part of 500 years. He secured his influence in the Dalmatian Romanized settlements against two Slavic peoples, the Croats and the Narentines, freed Venice from a 50-year-old taxation to the latter, and started Venice's expansions by conquering the islands of Lastovo (Lagosta) and Korčula (Curzola) and acquiring Dubrovnik (Ragusa).

These actions marked the beginning of the Stato da Màr, Venice's overseas dominion, and laid the foundation for its maritime empire. Because of these achievements, he is sometimes referred to as "the Great doge".

Source: Wikipedia — https://en.wikipedia.org/wiki/Pietro_II_Orseolo