I think the events which took place would depend on the time period.
If the Western Powers decided to invade during or just before an event like the Taiping Rebellion, then I think that its possible that both sides would form a temporary alliance (See WWII, Nationalists and Communists), to drive out the invaders. And no doubt it would be horribly bloody, but I think China would, in the end, win, becuase in a war of attrition, China always wins, especially when Europeans have to ship troops to China in a rather expensive manner. China absorbed about 50,000,000 dead between 1850 and 1860, I doubt a few thosand Europeans could do better than that.
In some alernate period, the Europeans might face guerilla warfare or a 'boxer rebellion', but I think they could hold on to coastal cities if they were determined. Going inland would be a mistake.
If the Western Powers decided to invade during or just before an event like the Taiping Rebellion, then I think that its possible that both sides would form a temporary alliance (See WWII, Nationalists and Communists), to drive out the invaders. And no doubt it would be horribly bloody, but I think China would, in the end, win, becuase in a war of attrition, China always wins, especially when Europeans have to ship troops to China in a rather expensive manner. China absorbed about 50,000,000 dead between 1850 and 1860, I doubt a few thosand Europeans could do better than that.
In some alernate period, the Europeans might face guerilla warfare or a 'boxer rebellion', but I think they could hold on to coastal cities if they were determined. Going inland would be a mistake.