Complex sentence: During World War I, Gladys met Major William John Frederick Halliday (Distinguished Service Order), a Royal Artillery officer born in London in 1882 and affectionately referred to as'Fred'.
Split into simpler sentences: During World War I, Gladys met a Royal Artillery officer called Major William John Frederick Halliday (Distinguished Service Order). He was born in London during 1882 and was affectionately referred to as'Fred'.