Mislav was the Duke of Littoral Croatia in 835–845.

Mislav succeeded Vladislav

Vladislav of Croatia

Vladislav was a nephew and successor of Duke Borna of Littoral Croatia. He reigned, as Duke of Littoral Croatia, from February 821 to ca. 835.Most information about Vladislav is carried by the Royal Frankish Annals when it speaks about Borna's death...

 as the Duke of Littoral Croatia. He ruled from Klis

Klis

Klis is a village located around a mountain fortress bearing the same name. It is located in central Dalmatia, Croatia, located just northeast of Solin and Split near the eponymous mountain pass...

 in central Dalmatia

Dalmatia

Dalmatia is a historical region on the eastern coast of the Adriatic Sea. It stretches from the island of Rab in the northwest to the Bay of Kotor in the southeast. The hinterland, the Dalmatian Zagora, ranges from fifty kilometers in width in the north to just a few kilometers in the south....

, when he made Klis Fortress

Klis Fortress

The Klis Fortress is a medieval fortress situated above a village bearing the same name, near the city of Split, in central Dalmatia, Croatia. From its origin as a small stronghold built by the ancient Illyrian tribe Dalmatae, becoming a royal castle that was the seat of many Croatian kings, to...

 seat to his throne. Mislav was pious ruler. He built the Church of Saint George in Putalj (on the slopes of hill Kozjak

Mali Kozjak

Kozjak, also known as Mali Kozjak or Primorski Kozjak is a mountain located above the town of Kaštela in Dalmatia, Croatia....

). Today's Kaštel Sućurac

Kaštel Sucurac

Kaštel Sućurac is a town within the administrative area of Kaštela in Dalmatia, Croatia.A noted element of the ancient history of this region is Diocletian's Palace in nearby Split, which structure was constructed in the period 293 to 305 AD....

 got its name after the village of sv. Jure (Saint George), named after that church.

He is chiefly known for signing a treaty with Pietro Tradonico

Pietro Tradonico

Pietro Tradonico , an Istrian by birth, was the Doge of Venice from 836 to 864. He was, according to tradition, the thirteenth doge, though historically he is only the eleventh. His election broke the power of the Participazio. He was illiterate, and forced to sign all state documents with the...

, doge

Doge of Venice

The Doge of Venice , often mistranslated Duke was the chief magistrate and leader of the Most Serene Republic of Venice for over a thousand years. Doges of Venice were elected for life by the city-state's aristocracy. Commonly the person selected as Doge was the shrewdest elder in the city...

 of Venetian Republic

Republic of Venice

The Republic of Venice or Venetian Republic was a state originating from the city of Venice in Northeastern Italy. It existed for over a millennium, from the late 7th century until 1797. It was formally known as the Most Serene Republic of Venice and is often referred to as La Serenissima, in...

 in 839, which led to the growth of Croatian sea power. Duke Mislav maintained good relations with the neighbouring coastal Cities of Byzantine Dalmatia unlike his predecessor, which also led to the growth of Croatian sea power as Mislav modelled Croatian ships in the likehood of the Neretvians and Venetians

Republic of Venice

The Republic of Venice or Venetian Republic was a state originating from the city of Venice in Northeastern Italy. It existed for over a millennium, from the late 7th century until 1797. It was formally known as the Most Serene Republic of Venice and is often referred to as La Serenissima, in...

.

Mislav was succeeded by Trpimir I

Trpimir I of Croatia

Trpimir I was a duke of Croatia in 845–864, and the founder of the Croatian House of Trpimirović. Although he was formally vassal of the Frankish Emperor Lothair I, Trpimir used Frankish-Byzantine conflicts to rule on his own.-Reign:...

after his death in 845.