There are several claims of 'wars extended by diplomatic irregularity', often by a small country named in a
declaration of war being accidentally omitted from the concluding
peace treaty of a wider conflict. These alleged extended wars have only been "discovered" after the fact, and had no impact during the long period (often hundreds of years) they were supposedly
de jure in force.
The "discovery" of an extended war is often an opportunity for a ceremonial peace to be contracted by local authorities.
Such a situation is to be distinguished from that of parties deliberately avoiding a peace treaty when political disputes outlive military conflict, as in the
Kuril Islands dispute between Japan and Russia.
Alleged extended wars
Notes
1. Saudi Aramco World, (bottom of page}
2. Spurious reported date; there was no ceremony as there was no historical conflict between the countries of any kind.
3. See Swedish historian Ulf Sundberg's debunking of the war.
4. Montenegro, Japan to declare truce
5. "World War I Ends in Andorra", UPI story in the New York Times, Sep 25, 1958. p. 66. A number of sources say 1939, but there is no period confirmation for this.
6. ''Inside Latin America'', John Gunther, Harper and Brothers, 1941