Complex sentence: To counter the kidnapping attempt, the Aizu and Satsuma domains led the defense of the Imperial palace, but during the incident, the rebels put Kyoto into fire, starting with the residence of the Takatsukasa family and the one of a Choshu official.
Split into simpler sentences: To counter the rebel's kidnapping attempt, the Aizu and Satsuma domains led the defense of the Imperial palace. However, during the attempt, the rebels put Kyoto to fire, starting with the residence of the Takatsukasa family, and that of an Choshu official.