Suppose that the Chinese Civil War ended in 1949/'50s, with the Nationalists fleeing to Taiwan. However, perhaps with U.S. aid, they managed to hold on to a province (or at least a city) or two in southern China. But for all intents and purposes, Taiwan is Nationalist China. The border between China proper and the tiny ROC areas in the south quickly become one of the heaviest defended places in the world.
Where can we draw a line? Which areas were last to fall?
Where can we draw a line? Which areas were last to fall?