A struggle for succession in the mid-twelfth century gave the Fujiwara an opportunity to regain their former power. Fujiwara no Yorinaga sided with the retired emperor in a violent battle in 1156 against the heir apparent, who was supported by the Taira and Minamoto (Hōgen Rebellion). In the end, the Fujiwara were destroyed, the old system of government supplanted, and the insei system left powerless as bushi took control of court affairs, marking a turning point in Japanese history. In 1159, the Taira and Minamoto clashed (Heiji Rebellion), and a twenty-year period of Taira ascendancy began.

Answer this question, if possible (if impossible, reply "unanswerable"): What struggle occured in the 1200's?
unanswerable