The correspondence of King George the Third from 1760 to December 1783

It's the correspondence of George III who was your king until George Washington & Co fought the War of Independence and you exchanged one George for another in 1776.

This correspondence spans the years before, during and after the above event and, therefore, is prime source material for learning about the founding of what is now the United States of America.

Of course, there's also the movie...