Final answer:
Empress Dowager Cixi opposed Emperor Guangxu's reforms known as the Hundred Days' Reform, imprisoned him, and ended the reform efforts in the late Qing Dynasty.
Step-by-step explanation:
The historical figure you're referring to is Empress Dowager Cixi, who became a dominant force at court during the late Qing Dynasty. Emperor Guangxu attempted to modernize and reform China through his Hundred Days' Reform, but Cixi opposed these reforms, believing that they would lead to the downfall of China due to foreign influence. Her actions included imprisoning the emperor and putting an end to the reform efforts, thereby maintaining traditional power structures and resisting the push for westernization. Cixi's intervention demonstrated the complexities of power dynamics within the Qing court and set the stage for continued struggles between traditionalists and reformists in China.