Diplomacy is the art of being able to say "nice doggie" until you have time to pick up a rock
origin uncertain; frequently misattributed to Will Rogers
Diplomacy means all the wicked devices of the Old World, spheres of influence, balances of power, secret treaties, triple alliances, and, during the interim period, appeasement of Fascism.
Diplomats are just as essential to starting a war as soldiers are for finishing it...You take the diplomacy out of war and the thing would fall flat in a week.
There are few ironclad rules of diplomacy but to one there is no exception. When an official reports that talks were useful, it can safely be concluded that nothing was accomplished.