Italy will Kill the Euro - Not Spain or Portugal

As Scandinavian schemes go, this one worked too perfectly. No one wanted to convert one currency to another. Between 1905 and 1924, no exchange rates among the three currencies were available. When Norway became independent, the irate Swedes dismantled the moribund Union in an act of monetary tit-for-tat.

The SMU had an unofficial central bank with pooled reserves. It extended credit lines to each of the three member countries. As long as gold supply was limited, the Scandinavian Kronor held its ground. Then governments started to finance their deficits by dumping gold during World War I (and thus erode their debts by fostering inflation through a string of inane devaluations). In an unparalleled act of arbitrage, central banks then turned around and used the depreciated currencies to scoop up gold at official (cheap) rates.

When Sweden refused to continue to sell its gold at the officially fixed price - the other members declared effective economic war. They forced Sweden to purchase enormous quantities of their token coins. The proceeds were used to buy the much stronger Swedish currency at an ever cheaper price (as the price of gold collapsed). Sweden found itself subsidizing an arbitrage against its own economy. It inevitably reacted by ending the import of other members' tokens. The Union thus ended. The price of gold was no longer fixed and token coins were no more convertible.

The East African Currency Area is a fairly recent debacle. An equivalent experiment, involving the CFA franc, is still going on in the Francophile part of Africa.

The parts of East Africa ruled by the British (Kenya, Uganda and Tanganyika and, in 1936, Zanzibar) adopted in 1922 a single common currency, the East African shilling. The newly independent countries of East Africa remained part of the Sterling Area (ie, the local currencies were fully and freely convertible into British Pounds). Misplaced imperial pride coupled with outmoded strategic thinking led the British to infuse these emerging economies with inordinate amounts of money. Despite all this, the resulting monetary union was surprisingly resilient. It easily absorbed the new currencies of Kenya, Uganda and Tanzania in 1966, making them legal tender in all three and convertible to Pounds.

Ironically, it was the Pound which gave way. Its relentless depreciation in the late 60s and early 70s, led to the disintegration of the Sterling Area in 1972. The strict monetary discipline which characterized the union - evaporated. The currencies diverged - a result of a divergence of inflation targets and interest rates. The East African Currency Area was formally ended in 1977.

Not all monetary unions ended so tragically. Arguably, the most famous of the successful ones is the Zollverein (German Customs Union).

The nascent German Federation was composed, at the beginning of the 19th century, of 39 independent political units. They all busily minted coins (gold, silver) and had their own - distinct - standard weights and measures. The decisions of the much lauded Congress of Vienna (1815) did wonders for labour mobility in Europe but not so for trade. The baffling number of (mostly non-convertible) different currencies did not help.

The German principalities formed a customs union as early as 1818. The three regional groupings (the Northern, Central and Southern) were united in 1833. In 1828, Prussia harmonized its customs tariffs with the other members of the Federation, making it possible to pay duties in gold or silver. Some members hesitantly experimented with new fixed exchange rate convertible currencies. But, in practice, the union already had a single currency: the Vereinsmunze.

The Zollverein (Customs Union) was established in 1834 to facilitate trade by reducing its costs. This was done by compelling most of the members to choose between two monetary standards (the Thaler and the Gulden) in 1838. Much as the Bundesbank was to Europe in the second half of the twentieth century, the Prussian central bank became the effective Central Bank of the Federation from 1847 on. Prussia was by far the dominant member of the union, as it comprised 70% of the population and land mass of the future Germany.

The North German Thaler was fixed at 1.75 to the South German Gulden and, in 1856 (when Austria became informally associated with the Union), at 1.5 Austrian Florins. This last collaboration was to be a short lived affair, Prussia and Austria having declared war on each other in 1866.

Bismarck (Prussia) united Germany (Bavarian objections notwithstanding) in 1871. He founded the Reichsbank in 1875 and charged it with issuing the crisp new Reichsmark. Bismarck forced the Germans to accept the new currency as the only legal tender throughout the first German Reich. Germany's new single currency was in effect a monetary union. It survived two World Wars, a devastating bout of inflation in 1923, and a monetary meltdown after the Second World War. The stolid and trustworthy Bundesbank succeeded the Reichsmark and the Union was finally vanquished only by the bureaucracy in Brussels and its euro.