The Huescar-Danish War
Lasting from 1809 until 1981, the Huescar-Danish War was a rare example of a bloodless war within a real one. The Peninsular War saw Spain, Portugal, and Britain allied against the First French Empire, then under the rule of the legendary Napoleon Bonaparte. This conflict formed part of the Napoleonic Wars ending at Waterloo. Within the bloody and brutal Peninsular War, the bloodless Huescar-Danish War began. It long outlasted the Napoleonic Wars, lasting from 1809 to 1981 without a shot fired. When Denmark opted to support Bonaparte the council of the town of Huescar were outraged. A small town in the Granada province of southern Spain, Huescar had no authority to declare war on Denmark or any other sovereign state. That did not stop it from doing so.
As with the 335 Years' War, the declaration was forgotten about and no action was taken on either side all the way up until 1981. One of the longest bloodless wars in European history ended with an handshake between the mayor of Huescar and the Dutch Ambassador on an appropriately symbolic date—November 11, 1981, otherwise known as Armistice Day in many Western countries.
That's what I think too.
The Dutch Ambassador?? Surely, the Danish one...