Sage is the answer I’m sure
Poor air and water quality, insufficient water availability, waste-disposal problems, and high energy consumption are exacerbated by the increasing population density and demands of urban environments. Strong city planning will be essential in managing these and other difficulties as the world's urban areas swell.
If we are talking about the second world war, then then answer would be that the Chinese kept the Japanese busy fighting them, and in turn, about 800,000 of their troops. This gave the Americans, who were the main force against the Japanese during this time, a little breathing room with which to continue military operations.
Hope this answered your question.
