World War I: <a href="https://en.wikipedia.org/wiki/Kingdom_of_Romania" id="mwAQ4" rel="mw:WikiLink" title="Kingdom of Romania">Romania</a> signs a <a href="https://en.wikipedia.org/wiki/Treaty_of_Bucharest_(1916)" id="mwAQ8" rel="mw:WikiLink" title="Treaty of Bucharest (1916)">secret treaty</a> with the <a href="https://en.wikipedia.org/wiki/Allies_of_World_War_I" id="mwARA" rel="mw:WikiLink" title="Allies of World War I">Entente Powers</a>. According to the treaty, Romania agreed to join the war on the Allied side.