You are contrasting the Revolutionary War against a war a century later. The ability to muster, transport, and support that many troops depends upon modern ind

You are contrasting the Revolutionary War against a war a century later. The ability to muster, transport, and support that many troops depends upon modern industrialization. Maintaining war against the Americans in the late 1700s was brutally expensive for Britain--with minimal ability to recover the costs after they "won". And this isn't even considering the fact that being part of the British army and navy was horrifically terrible--deserting to the American side was almost always an improvement unless you were an officer. If France and Spain hadn't been present in North America, Britain might have just told the colonies to sod off rather than fight a war.