Oeselians

On the eve of Northern Crusades, the people then residing in Saaremaa were described in the Livonian Rhymed Chronicle: "The Oeselians, neighbors to the Kurs (Curonians), are surrounded by the sea and never fear strong armies as their strength is in their ships.

"[3] The Chronicle of Henry of Livonia describes a fleet of sixteen ships and five hundred Oeselians ravaging the area that is now southern Sweden, then belonging to Denmark.

In the XIVth book of Gesta Danorum, Saxo Grammaticus describes a battle on Öland in 1170 in which the Danish king Valdemar I mobilised his entire fleet to curb the incursions of Couronian and Estonian pirates.

According to the legend in the chronicle, Tharapita was born on a forested mountain in Virumaa (Latin: Vironia), mainland Estonia from where he flew to Oesel, Saaremaa.

[7] In 1206, the Danish army led by king Valdemar II and Andreas, the Bishop of Lund landed on Saaremaa and attempted to establish a stronghold without success.

In 1220, the Swedish army led by king John I of Sweden and the bishop Karl of Linköping conquered Lihula in Rotalia in Western Estonia.

In 1222, the Danish king Valdemar II attempted the second conquest of Saaremaa, this time establishing a stone fortress housing a strong garrison.

Oeselians accepted Christianity again by signing treaties with the Livonian Order's Master Andreas de Velven and the Bishopric of Ösel-Wiek in 1241, setting penalties for pagan rituals.

The 1255 treaty included unique clauses concerning the ownership and inheritance of land, the social system, and exemption from certain restrictive religious observances.

On 24 July 1343, during St. George's Night Uprising, the Oeselians killed all the Germans on the island, drowned all the clerics and started to besiege the Livonian Order's castle at Pöide.