Nathan Hale's Hazardous Tales: Treaties, Trenches, Mud, and Blood:

Nathan Hale's Hazardous Tales: Treaties, Trenches, Mud, and Blood By: Nathan Hale
Non-Fiction: History, Graphic Novel, Humor, Children's 128 pages
Book Count: 20

This book goes over the whole of WWI.  Due to the hangman's love of animals, all the countries are represented by different animals (with little hats.)  This makes it actually easier to read the story, as even not in uniforms you can tell where everyone is from. Most places are their national animal, symbol, or other connected creature.  A few are different animals just because their animal was already taken, two are a pun.   Austro-Hungary is a griffin, Serbia a wolf, Russia a bear, Germany an eagle, France the Gallic rooster, Belgium a lion, The UK a bulldog, the USA a bunny (because there was already an eagle,) Australia a kangaroo, Canada a beaver, New Zealand a kiwi, India a tiger, France's African colonies were water buffalo, the Ottoman Empire an otter, Italy a cat (maybe a mountain lion,) Greece is a phoenix, Bulgaria a bull,  and Japan was a tanuki ( the raccoon dog.)  
For being a comic of animals in hats, this book does a better job explaining WWI then any school history book or class that I have ever had. It includes the main causes of the war, details of some of the major battles, as well as more personal stories to give a balanced look at the war.