For nearly 2 centuries, Denmark was at
war with the Spanish town of Huéscar –
but not a single shot was fired, and no
one was killed. After war was declared in
1809, everyone completely forgot about
it, so there were never any battles. A
peace treaty was finally signed in 1981,
when a historian happened upon the
official declaration of war and realized
the countries technically should have
been fighting each other for
the past 172 years. Source Source 2 Source 3