Europe is tough on American diplomats. It is so old. European cultures are piled on top of each other like logs. Europe has lots of countries and they keep changing their borders, even the small ones. Swing a cat on the Continent and you’ll probably hit a customs inspector. And there have been so many wars and revolutions in Europe, so many monarchs and empires, so many philosophers and artists and whatnots that it is hard to keep them all straight.
Europeans are always squabbling with each other, and an American diplomat is somehow supposed to understand all this, or pretend that he does, and to send messages back to Washington to explain what all these foreigners are up to. It is an impossible task.
Only a handful of American envoys has ever got the hang of it. In the years immediately after Independence, however, President Washington sent two extraordinary emissaries to Europe. John Adams was the Yankee doodle who went to London, establishing his embassy in Grosvenor Square. He was largely ignored by his official British hosts and he returned to America some years later, grumbling all the way.