Your assertion is that the President - by meeting with anyone - establishes diplomatic relations? Congress by law establishes such relations. Anything else is simply a meeting.
Lincoln didn't invade a foreign country and he didn't exceed his constitutional authority.
The blockade extended - by international law - official recognition of a foreign government.
Where does it say that?
Your assertion is that the President - by meeting with anyone - establishes diplomatic relations?
I never suggested that a simple meeting established diplomatic relations. I said that, given the southern demand that Lincoln recognize them as a sovereign nation, there was nothing to talk about.
The blockade extended - by international law - official recognition of a foreign government.
Utter nonsense. Not a single foreign government recognized confederate independence.