After the death of King Zvonimir, politically turbulent times followed in Croatia. Two sides found themselves in conflict. On one side was the widow of King Zvonimir, Jelena, who wanted to bring her brother, the Hungarian King Ladislav, to power. This idea was opposed by the majority of the Croatian nobility, the high clergy and Dalmatian towns. They managed to bring Stephen II, the son of the previous king Petar Krešimir IV, to power. But his imminent death led to another struggle for the throne. This time, the winner was Jelena, at whose invitation Ladislav entered Croatia and occupied the area from the Drava to the Chapel. The nobility in the unoccupied territory south of Gvozd did not accept this and they chose their king, Peter. It is not known whether he was crowned, nor the years of his reign, but it is believed that he was from the old noble family Snačić. In the 19th century, Franjo Rački mistranslated "n" to "v" and thus became popularly known as Svačić. Like the Croatian kings before him, he chose the city of Knin as his capital.

After the death of the Hungarian king Ladislav, his nephew Koloman came to power and decided to take full power in Croatia. Finding out that Koloman was heading towards Dalmatia with his army, King Petar met him. The battle took place in 1097. The exact location of the battle itself is unknown. According to traditional tradition, it happened somewhere around the mountain Gvozd, but it is also possible that the location was closer to the town of Knin. After a fierce battle, Koloman prevailed, and King Petar himself was among the killed Croats. Since then, according to folklore, the mountain has been called Peter's Mountain (Petrova Gora). Thus, with the death of King Peter, Croatia lost its independence for the next 800 years. On the occasion of the 900th anniversary of his death, a monument was erected in his honor near the place where he was born, above the island of Visovac in the Krka National Park.