Of the first six books in the top ten best sellers of 1917, three of those make reference to the First World War (AKA The Great War). The war, after all, was going on at the time so it's only natural that popular books would make some mention of it.
Of those three, two also reference the 2nd Boer War, which is why I've also made a detour to learn more of that conflict by reading The Great Boer War by Arthur Conan Doyle.
As I've mentioned in an earlier post, I've finished the first six in the list and have started on number seven, In the Wilderness by Robert S. Hichens. At this point, there is absolutely no question that I read this book in 2014, when I had read three other novels by Hichens as well. 2014 was the year my first Kindle was damaged beyond repair while flying to Dumaguete from the U.S. and I may simply have forgotten to take note of In the Wilderness at the time. That would explain why I don't have an earlier copy of the e-book.
Most of the book is coming back to me as I reread it. I had forgotten that this book also references the 2nd Boer War. At this point in the novel, the fighting at Ladysmith, Mafeking and Magersfontein had been fought and had led to a call for British men to volunteer to serve in the army. Dion, the protagonist of In the Wilderness has volunteered and is on a ship bound for South Africa.
At this point in Conan Doyle's book, I am just learning of Ladysmith, Mafeking and Magersfontein.
As it's been more than three years and probably 100 books since my reading of In the Wilderness, and I don't recall if Hichens mentioned the First World War in addition to the Great Boer War. I'll find out soon enough.