Tolkien actually fought in the World War and was trying to make a anti-war and anti-industrialization message.

For example he portrays Melkor (the ultimate evil in his lore) as the Maia (think Catholic saint) responsible for Industrialization, where one of his greatest achievements was building a fortress that was a factory that had chimneys that spewed coal smoke...

Even artisan characters were often portrayed negatively (Sauron, that made the Rings of Power, or the guy that made the Silmarils and then people commited genocide and other atrocities because of them).

One of the most famous obviously war-inspired scene Tolkien wrote, were the dead marches, that are absolutely creepy and repulsive, and they were basically a description of the terrain during the Battle of the Somme, where he was physically present in the trenches fighting.