Picking up on my kick for historical stuff I didn't know much about before, I found this one and have to admit I was uncertain about one of the very things mentioned in the book: Was the Lusitania sunk connected to the First World War, or the Second? It was the First, and in fact, not three years after the Titanic, which may explain why this ship doesn't get the attention the Titanic does. It also doesn't make as exciting a movie, since (as I also did not know) it sank within sight of land, in relatively shallow water.
It was also, unlike the Titanic, a deliberate sinking; a German submarine (U-boat) did the Lusitania in, and that's common enough knowledge; less familiar is the interplay between Germany and Britain which led to that sinking, including Britain's naval blockade of Germany and the attempt by a younger Winston Churchill, as Lord of the Admiralty, to make use of America as a supplier.
Butler brings the incident to life sidelights like a short history of submarine warfare and behind the scenes looks at the personalities involved: in America, the interplay between Woodrow Wilson as President, William Jennings Bryan (yes, of the Scopes trial) as Secretary of State, and Bryan's assistant Lansing, didn't help matters inasmuch as Wilson and Lansing each disliked Bryan for their own reasons.
All in all, another profitable historical reading quest.