From the lurker -
Wars generally puch development further during their duration, as they create jobs and stimulate the economy.
After a war, the number of jobs drops dramatically, and there are alot more people looking for them, so other industries are explored and expanded to try to keep the economy going.
We are doing the effect on Australia's economy in WWI, and the above at least happened then. You could only assume that in the US civil war did the same.