Duke Mislav, who in 835 had succeeded Vladislav as the Duke of Littoral Croatia, rules from Klis Fortress in central Dalmatia.

A pious ruler, he builds the Church of Saint George in Putalj (on the slopes of the hill Kozjak).

He is chiefly known for signing a treaty in 839 with Pietro Tradonico, doge of the Venetian Republic, that leads to the growth of Croatian sea power, as Mislav models Croatian ships after those built by the Neretvians and Venetians.

Unlike his predecessor, Mislav maintains good relations with the neighboring coastal cities of Dalmatia.

The election of Pietro Tradonico as Doge of Venice in 836 breaks the power of the Participazio.

An illiterate, he is forced to sign all state documents with the signum manus.

A warrior, not an administrator, he fights the Saracens of Bari and Taranto, who had earlier defeated Venice in the Battle of Sansego, on an island south of Pola.

Pietro Tradonicio has to deal not only with Saracen pirates, but with Slavs as well.

He leads a large fleet against the Narentines in 839 to punish them for raiding and slaughtering several Venetian traders returning from Benevento in 834–835.

He makes peace with Duke Mislav of the Croats of Dalmatia and a Narentine prince by the name of Družak (Drosaico, Marianorum judice).

Orso I Participazio, the fourteenth (traditional) and twelfth (historical) Doge of Venice, is elected in 864 immediately after the assassination of his predecessor, Pietro Tradonico, probably by acclamation.

By the end of the year, the assassins are captured, convicted, and executed, probably beheaded.

Orso continues, like Tradonico, to fight the pirates, Slavic or Saracen, that ply the Adriatic coast, aided by a newly constructed fleet of larger ships.