The tiny (three miles by five miles) European Duchy of Grand Fenwick, supposedly located in the Alps between Switzerland and France, proudly retains a pre-industrial economy, dependent almost entirely on making Pinot Grand Fenwick wine. However, an American winery makes a knockoff version, "Pinot Grand Enwick", putting the country on the verge of bankruptcy.
The prime minister decides that their only course of action is to declare war on the United States. Expecting a quick and total defeat (since their standing army is tiny and equipped with bows and arrows), the country confidently expects to rebuild itself through the largesse that the United States bestows on all its vanquished enemies (as it did for Germany through the Marshall Plan at the end of World War II).
Instead, the Duchy defeats the mighty superpower, purely by accident. Landing in New York City, almost completely deserted above ground because of a city-wide disaster drill, the Duchy's invading "army" (composed of the Field Marshal Tully Bascomb, three men-at-arms, and twenty longbowmen) wanders to a top secret government lab and unintentionally captures the "Q-bomb" (a prototype doomsday device that could destroy the world if triggered) and its maker, Dr. Kokintz.
The invaders from Fenwick are sighted by a Civil Defense Squad and are immediately taken to be "men from Mars" when their mail armor is mistaken for reptilian skin. The Secretary of Defense pieces together what has happened (with help from the five lines in his encyclopedia on Grand Fenwick and the Fenwickian flag left behind on a flagpole) and is both ashamed and astonished that the United States was unaware that it had been at war for two months.
With the most powerful bomb in the world now in the smallest country in the world, other countries are quick to react, with the Soviet Union and the United Kingdom offering their support. With the world at the tiny country's mercy, Duchess Gloriana, the leader of Grand Fenwick, lists her terms: all the nuclear weapons of the powerful nations must go through an inspection by impartial scientists and the "Tiny Twenty" (a joke about the "Big Three" Nations) should be formed, a group of twenty small nations so that small nations can get their voices heard as well as large ones. Soon Duchess Gloriana and Tully Bascomb get married, and during the wedding Dr. Kokintz discovers that the bomb is a dud and that the bomb Grand Fenwick used to threaten the world into obedience never had any power whatsoever. However, Dr. Kokintz decides to keep that fact to himself considering that the pretense still furthers the cause of world peace.
