Jules-Martin Cambon (5 April 1845 – 19 September 1935) was a French diplomat and brother to Paul Cambon.
As the ambassador to Germany (1907–1914) he worked hard to secure a friendly détente.
He was frustrated by French leaders such as Raymond Poincaré, who decided Berlin was trying to weaken the Triple Entente of France, Russia and Britain, and was not sincere in seeking peace.