World War 1, also called the Great War, lasted from 1914 to 1918, and involved many of the world's most influential nations.
Less than a month after the events on this page, on July 1st, the British Army would suffer over 57,000 casualties, making it the bloodiest day in the Army's history.
Hathaway's son was killed in the Battle of Jutland, off the coast of Denmark. This was the largest naval battle of World War I.
The Magdalene Grimoire is an invention of Gaiman's. It later makes an appearance in the comic books Green Arrow Volume 3 #9-10, which are collected in the graphic novel Green Arrow: Quiver.
Ellie is being read to from Through the Looking-Glass (1872), Lewis Carroll's sequel to Alice's Adventures in Wonderland (1865). They are now usually published together as Alice in Wonderland, a novel which is considered one of the classic examples of "literary nonsense," a style Gaiman often incorporates into his own dreamlike stories and dream sequences.
Read Through the Looking-Glass at Project Gutenberg.
Aleister Crowley (1875-1947) was a famous English occultist, known in his day as "the wickedest man in the world." Any practising occultist or dark magician of that period would certainly have come up against him.
Read Household Gods by Aleister Crowley at Project Gutenberg.
Burgess here invokes a variety of demonic entities from different sources. Namtar was a Mesopotamian god of death and controller of diseases, Allatu a Semitic underworld goddess, Morax a demonic teacher of liberal sciences, Naberius a demon who made men cunning, and Vepar a demon who controlled the sea. Klesh, Maymon, and the following names appear to be Gaiman's creations, but can be assumed to be similar beings.