Montenegro was at war with Japan for 100 years due to one of those legal technicalities that so often comes up in times of war.
During the Russo-Japanese War of 1904-05, Montenegro was a ally of Russia, but it was there only to provide moral support after the Russians helped them against the Ottoman Empire.
Japan won the war, but for some reason Montenegro was forgotten about, then it became part of Yugoslavia, then it became independent again. It was not until 2006 when the conflict was finally stopped officially.
QI is a visit to Cetinje the old capital. It is perched high up on a hill top. From 1878 the great powers had embassies there and today when touring the old capital you can see the splendid residences.