[Pelham]

“They unilaterally left.”

The British North American Colonies ‘unilaterally left’ 90 years earlier. King George reacted the same way that Lincoln did.

[DiogenesLamp]

The British North American Colonies ‘unilaterally left’ 90 years earlier. King George reacted the same way that Lincoln did.

Not quite. He simply wasn't as willing to get so many people killed as was Lincoln.

[ConservativeMind]

Perhaps, but there was 100+% representation of the South in everything, including the president (Buchanan) that the South left under, while in charge.

So, the South is the bird that pooped in the drinking water everyone had to use, then left, squawking that the water had poop in it.

[BroJoeK]

Pelham: "The British North American Colonies ‘unilaterally left’ 90 years earlier.
King George reacted the same way that Lincoln did."

Complete rubbish!
In fact, there was a vast difference between the 1776 Declaration of Independence and 1861 Declarations of Secession.
First & foremost, by July 1776 the British King & Parliament had already effectively declared war against the colonies and had been waging war for well over a year, hence the Declaration's indictment:

"He has plundered our seas, ravaged our Coasts, burnt our towns, and destroyed the lives of our people."

Nothing remotely resembling such necessary conditions existed in 1860 when Southern Fire Eaters began organizing to declare secession at pleasure.