In the late Qing Dynasty, it was a great event for the Qing Dynasty and even the Chinese nation to lead the Xiang army to the west and recover Xinjiang. Because he defended the territory of China, he was also called the greatest national hero in history. In the western expedition, Zuo was able to achieve such good results mainly because his army was equipped with very advanced weapons, so it was overwhelming when attacking.
Later, when they attacked the city in Eight-Nation Alliance, they also bought many advanced weapons, but they didn't use them. First of all, because of the difference between Manchu and Han, Manchu didn't trust the Han people at first, so it was very defensive, so it wasn't used, so it was given to Eight-Nation Alliance cheaply later.
Another reason is that Cixi declared war on the eight countries, mainly because she was encouraged by others. In this regard, Cixi is very self-aware. She knew that she and their imperial court things, even with the best weapons, were no match for Eight-Nation Alliance, but because of the limited quantity, even if she was equipped with the army, she might not be able to fight. If she came to the army again in the future, they couldn't resist, so she didn't really dare to fight at all, so she didn't fight for a long time afterwards.