Battle of Messines (1917) - Wikipedia
Ray, E. Lansing Collection, Collections
Has there ever been an instance where using animals was necessary or crucial in war? - Quora
American Military Vehicles of World War I - Land Locomotion
First Battle of Ypres - Wikipedia
Cheval de frise - Wikipedia
German soldier ww great war hi-res stock photography and images - Alamy
German cavalryman on the Eastern Front during WWI. : r/europe
A History of Europe, Chapter 14
German anti cavalry spike from Avenue Farm, near Messines
The Project Gutenberg eBook of The Children's Story Of The War (Volume 3), by Sir Edward Parrott, M.A., Ll.D.