Operator 5 #30

In the far reaches of High Asia, the Purple Empire had set up its factories and its smelters, to forge the most powerful weapon yet devised in military history. That weapon was a fleet of super-dreadnoughts equipped with a strange secret device to render our Defense Force helpless... In this gripping novel of the historic Purple Invasion, giant guns ashore and turret magic at sea hurl death at America's crumbling bulwarks as intrigue knifes the stout defenders. And Operator 5, Secret Service ace, becomes a man without a country, with death and disgrace as his only reward.