As the <a href="https://en.wikipedia.org/wiki/Treaty_of_Saigon_(1862)" id="mwfw" rel="mw:WikiLink" title="Treaty of Saigon (1862)">Treaty of Saigon</a> is signed, ceding parts of southern <a href="https://en.wikipedia.org/wiki/Vietnam" id="mwgA" rel="mw:WikiLink" title="Vietnam">Vietnam</a> to France, the guerrilla leader <a href="https://en.wikipedia.org/wiki/Trương_Định" id="mwgQ" rel="mw:WikiLink" title="Trương Định">Trương Định</a> decides to defy Emperor <a href="https://en.wikipedia.org/wiki/Tự_Đức" id="mwgg" rel="mw:WikiLink" title="Tự Đức">Tự Đức</a> of Vietnam and fight on against the Europeans.