This became a major problem for the Union and the coup de grace was delivered by the unprecedented financing needs brought on by the First World War. The LMU was officially dismantled in 1926 - but died long before. As the LMU was being formed, in 1867, an International Monetary Conference was convened. Twenty countries participated and discussed the introduction of a global currency. They agreed to use three major hard currencies but to equate their gold content so that we will be completely interchangeable.
Humanity seems to select the right course only after it tried all the wrong ones.
One wrong course was the Scandinavian Monetary Union. It worked so perfectly that no one wanted to changed the currencies and exchange rates were not available from 1905 to 1924, when Sweden dismantled the Union with the independence gained by Norway. The Scandinavian Kronor held well as long as gold supply was limited. I changed this situation governments dumped gold and inflated their currencies, engaging in competitive devaluations. Sweden saw through this ploy and refused to sell its gold in the officially fixed price.