Here's an interesting find: stuffed in one of the essays from Hendrik Hertzberg's Politics, we come across a National Review editorial, circa 1984, on the theory that a free media puts nations at a distinct disadvantage come wartime:

"Five years ago, liberal opinion predicted that Afghanistan would be the 'Soviets' Vietnam.' How could that be, without a free press and the freedom of opposition that liberalism also prescribes? … A society that has only Pravda may be less blessed than a society that has the New York Times, but it enjoys a strategic advantage.

Except that this was proved exactly wrong. Pravda put on a happy face, but eventually people in Russia did find out the truth about Afghanistan—as wounded veterans slowly returned to the country, wending their way through cities and towns, telling everyone about the horrors that transpired on the battlefield. And eventually the war—and the opposition to it, which was that much more vigorous when it finally burst through the dam of secrecy—helped bring down the Soviet Union. (Well, that and depressed oil prices, of course.) In fact, a freer press might have caught onto the fact that the Soviets were in a losing struggle against a determined population much, much earlier, and caused the country to withdraw rather than stay mired in a quagmire from which it had everything to lose and very little to gain. Not that this settles the broader debate here, but the idea that the Pravda conferred a "strategic advantage" doesn't hold up very well in retrospect.