三國協約
At the start of World War I in 1914, all three Triple Entente members entered it as Allied Powers against the Central Powers: Germany and Austria-Hungary. On September 4, 1914, the Triple Entente issued a declaration undertaking not to conclude a separate peace and only to demand terms of peace agreed between the three parties. Historians continue to debate the importance of the alliance system as one of the causes of World War I.