St. George's Night

It is St. George's Night, 1343, and Estonia has been subject to the rule of the Danish Crown and the Teutonic Order since the of the 1260s. Yet their rule has grown weak and their taxes heavy, and Estonia is in a ferment. Finally, on this night, it boils over. In a coordinated attack, all of the foreigners, both Germans and Danes, in Central Estonia are slaughtered. The rising spreads across Livonia, with the Estonians renouncing Christianity and killing their former overlords indiscriminately. Soon is under siege, abbeys and manors across Livonia are in flames, and the  calls on the Estonian leaders to negotiate. In our timeline, the leaders duly went to negotiate, only to be killed, leading to the defeat of the Estonian army and the suppression of the revolt. But what if an Estonian traitor had warned the leaders of the impending treachery, enabling the revolt to continue long enough for Sweden and Novgorod to take notice? How would the survival of a pagan Baltic state have changed the development of Eastern Europe and, eventually, the world? Welcome to the world of St. George's Night.

Point of Divergence
The leaders of the Estonian revolt, warned of the fate awaiting them if they negotiate, refuse to place themselves into the hands of the Livonian Order. As a result, the Estonian army remains sufficiently organized to evade destruction at the Battle of Warhill. This buys enough time for aid to arrive from Sweden, resulting in a long but ultimately successful revolt that establishes Livonia as a Duchy under the Swedish crown, albeit with paganism and a native Baltic aristocracy surviving.