Tolkien wrote in a letter in 1960 that "The Dead Marshes [a place north of Mordor] and the approaches to the Morannon [an entrance to Mordor] owe something to northern France after the Battle of the Somme". He took part in the battle between September and October 1916 as a signals officer, before being sent home with trench fever. According to many scholar, the metallic dragons that attack the Elves in the final battle of The Fall of Gondolin can be seen as tanks.