I had these in my eBay Watch List, and accidentally bought them. Boring story. However, I’m glad I did as they are a great find! I don’t believe this is a complete set, but it would be pretty hard to finish it, and it’s good reading anyway. The first ones were published in 1914, the first year of the war, and the last one in the set that I have was published a year before the war ended.
The first issue is interesting with things such as the chapter on airplanes, because at that point they were just used for reconnaisance and some very basic bombing, consisting of the passenger or even the pilot dropping the bomb from the side of the plane. It was all experimental in that first year. They quickly changed that.
Being more than a hundred years old, these aren’t in that great of shape, but very readable. I had to pay to have them shipped from Great Britain, but that was worth it. They are like big National Geographics from the time.