1. WINSTON CHURCHILL
Winston Churchill (pictured above) was already a key member of the British government in the early part of the war, but his part in the planning of the disastrous Gallipoli campaign dealt his reputation a huge blow. Feeling unwelcome and embittered, he made the stunning decision to quit Westminster and enlist as a soldier on the frontlines.
The conflict gave him a feeling of morbid exhilaration. As he wrote in a letter, "I am interested, geared up and happy. Is it not horrible to be built like that?" While he wasn't directly involved in any battles, Churchill did make dozens of journeys into No Man's Land, and endured the casual barrage of bullets and shells, before returning to frontline politics. Some have wondered if, during his time in the war zone, he ever entered the vicinity of his future nemesis, Adolf Hitler
2. WALT DISNEY
Long before he would create one of the most powerful entertainment companies on Earth, Walt Disney was a gung-ho teenager who found himself utterly enthralled by World War One, seeing it as a thrilling patriotic adventure. There was just one snag: he was too young to enlist. So, the determined boy applied to be an ambulance worker instead, even though his own father refused to sign his documentation, saying "I might be signing your death warrant."
Eventually, Walt did get to join up, but was disappointed when the Armistice was signed before he was able to get stuck in. Walt was dispatched to the battlefields to help treat wounded men and clean up the wrecked cities but he later said, "Everyone else was celebrating the end of the war, but all we knew was that we'd missed out on something big." By strange coincidence, he also happened to train alongside another enterprising young man - Ray Kroc, who would later create the McDonald's fast food empire.
3. ADOLF HITLER
Controversy still swirls around the future Fuhrer's time in the trenches. According to some accounts he was an energetic soldier who ran dangerous errands for the Bavarian Army, but other documents indicate he had a relatively cushy job and was mocked as an inept coward by his fellow soldiers. What is clear, however, is that Hitler was fervently committed to the cause of war, and his stringent obsessions made him a loner among the other men. Indeed, his closest friend may have been a dog he adopted in the trenches.
Present in many notorious battles of the war, including the Somme, Hitler escaped serious injury but was in hospital recovering from a mustard gas attack when news came that Germany had surrendered. He later turned this into a key chapter in his own mythology, saying "When I was confined to bed, the idea came to me that I would liberate Germany, that I would make it great." His belief that German soldiers had been "stabbed in the back" by the establishment would help propel him on his path to genocide and tyranny.
4. JRR TOLKIEN
The man who would effectively create the fantasy genre with his Lord of the Rings saga was a promising young academic when the war broke out. After suffering scorn from his peers and relatives for not enlisting straight away, Tolkien caved into the pressure and joined up. His letters home from the front line are a treasure trove of insights into the hierarchy of war - "Gentlemen are rare among the superiors, and even human beings rare indeed," he wrote. And, in another message: "The most improper job of any man... is bossing other men. Not one in a million is fit for it, and least of all those who seek the opportunity."
Embroiled in the horrors of the Somme, Tolkien was "lucky" enough to contract trench fever, and was sent back to England to recover. This likely saved him slaughter, and his experiences directly inspired the battle scenes in his later novels. The plucky character of Samwise Gamgee was also, in his Tolkien's own words, "a reflection of the English soldier, of the privates and batmen I knew in the 1914 war, and recognised as so far superior to myself."
5. CS LEWIS
Tolkien's friend and fellow fantasy pioneer, CS Lewis, was also thrown into the blood and mayhem of the Great War. He was actually too young to fight when the war began, and hoped it would all be over by the time he came of age. No such luck. The future author of The Lion, The Witch and The Wardrobe arrived in the Somme in time for his 19th birthday, and survived months of trench warfare. Like Tolkien, he contracted trench fever, but wasn't fortunate enough to be sent back home.
Instead, he recovered in France and carried on fighting before being eventually wounded by an exploding British shell. "Just after I was hit, I found that I was not breathing and concluded that this was death," he later wrote. "I felt no fear and certainly no courage. It did not seem to be an occasion for either."