Complex sentence: He was the most highly decorated British private soldier of the First World War but, by a supreme irony, he is most famous for sparing the life of a soldier who was later identified as Adolf Hitler, probably at Marcoing, France in September 1918.
Split into simpler sentences: He was the most highly decorated British private soldier of the First World War. He is most famous for allegedly sparing the life of a soldier who was later identified as Adolf Hitler, probably at Marcoing, France in September 1918.