John Juby completed an apprenticeship as a cabinet maker before he was called up as a National Serviceman at 20, serving as a corporal in the Royal Norfolk Regiment in Korea. After initial training, he was sent to Korea, celebrating his 21st birthday en route. His journey to Korea included a stop in Hong Kong, where he had a chance encounter with his uncle, a Royal Navy officer. In Korea, he was part of the pioneer platoon and looked after the Korean porters who introduced him to local food, often lacking in hygiene.
During his time in Korea, John Juby had various experiences that left a lasting impact. One of the most harrowing aspects of his service was dealing with the casualties, including his school friend, Roy MacDonald, who was killed by a mortar round. He also experienced the stress of friendly fire incidents and the harsh realities of war. Despite these hardships, he maintained a sense of duty and camaraderie with his fellow soldiers.