Could be:

In 1916, a 24-year-old British soldier named J.R.R. Tolkien went off to fight in World War I. He was stationed near the village of Bouzincourt, took part in the nearby Battle of the Somme and writes about the area in his diaries.

Jeff Gusky, an explorer and photographer who maintains a site called “The Hidden World of World War I,” believes Tolkien may have visited Bouzincourt’s caves, places where hundreds of soldiers took refuge during the Somme — and that some of his impressions ended up in “The Lord of the Rings.”

Others aren’t so sure. At any rate, no one questions Tolkien’s experiences as a soldier during World War I had an influence on The Lord of the Rings. He once wrote in a letter that “The Dead marshes and the approaches to the Morannon owe something to Northern France after the Battle of the Somme.”