Assuming the conquest was complete, Britain withdrew large portions of the army in preparation for the brewing opium war in China.

英国想当然地认为对阿富汗的征服已经结束，因此撤走了军队的大部分，以准备对中国发起酝酿已久的的鸦片战争。

The opium war of 1839 to 1842 was a major testimony to China's inability to defend itself against outside aggression.

1839年至1842年的鸦片战争是中国无力抵御外来侵略的重要证明。