Complex sentence: However, resistance to his rule continued, and Chongqing was retaken by Ming loyalists in the spring of 1645, he embarked on a campaign of terror to stamp out the remaining resistance in Sichuan.
Split into simpler sentences: However, resistance to his rule continued, and Chongqing was retaken by other forces. In 1645, he embarked on a campaign of terror to stamp out the remaining resistance in Sichuan.