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". In both cases, these are places where a great number of people died while fighting, and perhaps the sounds of artillery, bombs and so on can be compared to the drums used by orcs and goblin in the dwarf city of Moria before attacking the Fellowship.