Paul Kennedy's 1987 work, "The Rise and Fall of the Great Powers," is arguably one of the most influential works I have ever read and is mandatory reading in most collegiate international studies courses today. The author uses economic data to explain the rise and fall of (you guessed it) Great Powers from the 1500s up to today, explaining how European powers and later, the United States, rose to global dominance, supplanting China, the Mughals and Indian Princely States, and the Ottoman Caliphate.
The part of his work concerning the 20th century is engrossing, and I return to it again and again for enlightenment, peppering many of my online historical arguments with the statistics contained therein. For your reading and analytical pleasure, I present the following selected graphs from said work. I hope you find them as interesting as I do.
The thing that stands out is just how powerful the Soviet Union was on the verge of WW2. This is important, because in WW1, industrialized Germany annihilated Czarist, agrarian Russia. When the Bolsheviks came to power, they negotiated a separate peace with Germany, the Treaty of Brest Litovsk. By 1941, Russia's industrialization far surpassed Germany's.
Also, despite what many "new age" economic talking heads say, WW2 shows just how important manufacturing and industrial capability is during a time of warfare. The British, lulled into the doctrine of free and open trade, had decentralized their agricultural and industrial production to such a degree by 1939, that the vast majority of their food and key raw materials (which they had once produced domestically, albeit at higher cost) were sent overseas. On the one hand, this spared them from German bombs during the Blitz. On the other hand, it meant that everything needed to be transported by sea. Hitler's U-Boat campaign against Britain (which he never fully understood, was never fully committed to, and was never very enthusiastic about, despite the pleas of unorthodox admirals like Doenitz) almost brought Britain to her knees. After the war, Churchill said it was the only thing that really, truly worried him during the war. He knew Hitler would never be able to invade. He knew Hitler would not prevail in the Blitz. But he didn't know how long Britain's civilians could last if they were being starved of food, gas and key commodities from overseas. A service economy, even a high tech economy, count for nothing unless you can "make stuff."
Before WW2, Luftwaffe chief Hermann Goering said "America excels at making automobiles, but they cannot make fighter planes." History shows us that the industrial base to wage global war is largely dependent upon a strong, pre-existing peacetime industrial foundation. During wartime, these peacetime industries are merely "re-tooled" or converted from the production of consumer goods, to the production of weapons of war. One doesn't really have the ability to "industrialize" during wartime. Today, China is making enormous strides in this regard, and if we ever have a war with her, they may very well astound the world with their capacity for high-tech military production, on a scale never seen in world history. No doubt some old timers here will disagree with me, but old timers sometimes refuse to see the truth, blinded by the clouds of nostalgia.
Another interesting thing to note is how the Soviets, due to their utilization of a different economic system, were able to outproduce the Germans without spending as much. That said, the quality of what the Soviets produced in the 1930s was inferior to what the Germans produced, generally speaking. However, because the Soviets produced so many different things, they were able to see what worked, such that they stuck with the most successful tank, tank destroyer, fighter plane, and interceptor designs and these came to predominate in all Soviet production, easily accomplished due to high levels of economic centralization. The Germans, by contrast, actually produced an ever-increasing variety of things by the end of the war, due to the fact that their industry was increasingly decentralized by war's end---a conscious effort to minimize the destruction wrought by the Anglo-American aerial industrial bombing campaign.
This chart is actually rather amazing. It shows how much Germany and Russia suffered as a result of WW1, and how much they surpassed their pre-1914 industrial levels by the advent of WW2. I'm still amazed at what Stalinization did to Russia, and horrified when I realize how many people undoubtedly died to achieve these numbers.
One thing that these graphs also show, is that if the Axis Powers had any hope of victory, it had to be a quick victory. They had to clean-up at the table by the end of 1941 at the latest, before the Allies could fully re-tool their industry, and mobilize their economy and populations for total war. The sheer size of the Allied Powers, in terms of industrial capacity, population and the like gave them far more military potential than anything the Axis Powers could even dream of.
And I suppose a similar principle would have to guide any policy we would have in a possible future war with China. We would need a fast, lightening victory. If the war lasted too long, China would outproduce us, and get to a point where she could utilize and leverage her vastly superior population.