The Congress of Berlin was held in June and July 1878, the central relationship in it that between Disraeli and Bismarck. In later years, the German chancellor would show visitors to his office three pictures on the wall: "the portrait of my Sovereign, there on the right that of my wife, and on the left, there, that of Lord Beaconsfield". Disraeli caused an uproar in the congress by making his opening address in English, rather than in French, hitherto accepted as the international language of diplomacy. By one account, the British ambassador in Berlin, Lord Odo Russell, hoping to spare the delegates Disraeli's awful French accent, told Disraeli that the congress was hoping to hear a speech in the English tongue by one of its masters.