I agree with Jmat. The author is trying to describe the time and context with greater clarity. "Europe was waking up during the renaissance" = This is what was happening to Europe, or what Europe was doing during the many years of the renaissance. "After the American Civil War, Europe woke up to the realization that iron warships were the future." = This one, single event (the end of the civil war), did one, single thing to Europe.

It had started waking up but hadn't finished. Since the action was in the past but ongoing at the referenced time, past continuous is used.