King James I wrote a book in the 17th century arguing that the King is the Father of the country, and just as it is not right for children to rebel against their father, it is never right for citizens to rebel against their king.
This principle of the "divine right of Kings" was adopted by most philosophers. In other words, warring against your own government was always immoral.
This principle was challenged when Charles I was king of England. Members of Parliament believed the king was a criminal. The notion arose as to the acceptability of a legitimate rebellion. Oliver Cromwell was a member of Parliament who set forth the argument that when a King becomes corrupt, it is not only allowable, but right to overthrow that king. This was the backdrop of the thought of an English philosopher named John Locke.
The use of gunpowder transitioned the world out of the medieval period.
Locke's philosophy would be adopted by later revolutionaries such as Thomas Jefferson and the Americans. King George III was largely operating under the old principle of "the King is never to be overthrown."
DECISION: When, if ever, is it proper to attempt to overthrow your government?