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 (i.e., 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.