Tomb of the Unknown Soldier services connected with their 'monumental' graves (as presumably newly conceived, and in any case approved, by their respective armies) on Armistice Day 1920 (the burial itself taking place later in January of the following year in France). In the UK, the Tomb of the Unknown Warrior was created at Westminster Abbey, while in France "La tombe du soldat inconnu" was placed in the Arc de Triomphe. The idea of a symbolic Tomb of the Unknown Soldier then spread to other countries. In 1921, the United States unveiled its own Tomb of the Unknown Soldier, Portugal its Túmulo do Soldado Desconhecido,
The Unknown Terror more deeply into the film, peering through the suds to find more complex meanings. American academic film historian Rob Craig notes a religious theme within "The Unknown Terror". He writes that the songs performed by Sir Lancelot "are well used as purveyors of taboo folk wisdom, with one line, 'He's got to suffer to be born again,' vividly foreshadowing the ensuing religious emphasis on the film." As an example, Craig writes that when he's asked about the Cave of the Dead's precise location, "Ramsey chuckles, 'I can show you how to find that - it's their purgatory ...' as he