<a href="https://en.wikipedia.org/wiki/Treaty_of_Nanking" id="mwew" rel="mw:WikiLink" title="Treaty of Nanking">Treaty of Nanking</a> comes into effect, <a href="https://en.wikipedia.org/wiki/Hong_Kong_Island" id="mwfA" rel="mw:WikiLink" title="Hong Kong Island">Hong Kong Island</a> is ceded to the British "in perpetuity".