In English history, Lancaster and York contended for the Crown, then Henry VII Tudor resolved the conflict because he was equally descended from both Houses. The Civil War in the following century was between King and Parliament. We still live in this history. At least, I live in Lancaster in a constitutional monarchy and York gave its name to New York. Poul Anderson showed us an alternative history with a different outcome of the English Civil War.
In SM Stirling's Emberverse, Rudi Artos Mackenzie unites the Bearkillers with the Mackenzies while his and Matti's children will unite Rudi's two heritages with House Arminger. However, their High Kingdom of Montival fights new external enemies before it even exists except in name.
In each history, every resolved conflict is followed by another.