During World War I, Sir Arthur Conan Doyle experienced what, for him, was the most important moment of his life, but it had nothing to do with deaths or battles. Since his days in Southsea, he had been cautiously interested in spiritualism. In late 1915, something convinced him that its claims were completely true, and he became a devout spiritualist. After years of study and investigation, he wrote, [I felt at last no doubt at all.] No one knows exactly what this decisive event was, but it probably involved a message from beyond the grave, perhaps from Jean's brother Malcolm Leckie, who had just been killed at the front.
It has often been said that Conan Doyle's conversion to spiritualism was caused by his many losses during the war. In fact, his conversion happened before the most painful losses—the deaths of his son and brother. Still, it certainly did bring him consolation when they died, and when his beloved mother died a few years later. [It is,] he wrote, [a revolution in religious thought… which gives us an immense consolation when those who are dear to us pass behind the veil.]