He was fairly successful , A treaty was signed with Mexico to annex the strip of land known as the Gadsden Purchase. A trade treaty was signed with Japan. A dispute with Austria involving an American accused of espionage was settled favorably.
The big failure was his attempt to purchase Cuba from Spain which ended with the brouhaha known as the Ostend Manifesto.
You realize that there was no telegraph or telephone connection with Europe or Japan, so Pierce was dependent on his ministers to handle the actual negotiations.
He was president which makes him commander and chief. All presidents are.
What does Chief of Diplomat mean?
He was the president and not a diplomat .
The President
The Chief Diplomat is the President of the United States, who at the moment is Donald Trump. Hillary Clinton is not, and has never been, Chief Diplomat.
chief diplomat
Benjamin Franklin
He was not very effective.
Barack Obama
carter
chief diplomat
The Commander in chief is the US President.One of the six major roles of the President of the United States is Chief Diplomat. As chief Diplomat, the President's job is to conduct foreign policy by directing the actions of American ambassadors and signing treaties and trade agreements with leaders of foreign nations