Why can 4,000 British troops overthrow millions of Manchu troops?

Although the Manchu dynasty had many soldiers, it controlled many and divided and ruled. Who cares about whose territory, don't expect others. Sweep your own snow, don't expect others to work for you.

The British army used the maneuverability of seagoing ships to attack the sensitive and weak parts of the Qing Dynasty.

The Qing army's attack on the British army was completely unprepared and deployed.

The Qing army lacked a minimum understanding of the enemy. Even watching people walk in goose steps, they thought that foreigners' knees would not bend, and thus came to the understanding that they would fall as long as they picked them with bamboo poles-can such an army compete with our Eight Banners soldiers? Don't laugh, it's true. On the battlefield, there have really been soldiers charging with bamboo poles to provoke each other's feet.

Now let's take a look: the British army turned to the north because it could not defeat the besieged Qing army in Guangzhou. In the jubilation of the Manchu Dynasty, the raid on Dagukou in Tianjin was a fatal blow, and the emptiness of the capital was still close at hand. So the court negotiated with the British army, and commercial disputes did not need to be fought. When you go back to Guangzhou, we will definitely remove the cannon and Lin Zexu. So the British army retreated to the south. When the Qing dynasty removed the cannon and dismissed Lin Zexu, the British army immediately launched an attack. I would like to ask: how can the army be unbeaten without unified command and the various armies are in a mess? If you stick to your gun in the same place, such as Humen Fort, as an opponent of British muskets, how can you fight alone? Without reinforcements, we can only wait for death. Of course, Guangzhou should be able to reorganize the national army and recover it, but where is the army and where to mobilize it? That army is nominally owned by the state, but in fact it belongs to the great warlord. What are the advantages and benefits of moving home to Guangzhou to fight? The court slowly talked to these warlords? What if the British army goes north again and comes to Beijing again? Let's get married as soon as possible. Land, money and food come from all over the country. Anyway, we don't want a penny from the court.

So the Opium War led to the Qing Dynasty being defeated by 4,000 British troops.