Ernest Marks was educated at St. Stanislaus' College, Bathurst and then started work in 1903 as a journalist for the Australian Star, remaining on its staff after a takeover by Sun Newspapers Ltd. Marks became the Sun's chief law reporter between 1909 and 1935, reporting on practically every jurisdiction of the Supreme Court in that time. He was a foundation member of the Australian Journalists' Association.
Marks's paternal grandfather fought with Napoleon Bonaparte, 1796-97, at the battles of Lodi, Rivoli and Arcola and in the Marengo Campaign of 1800. His father fought with the troops of Napoleon III in the Crimean War of 1854-56. Ernest Marks, who claimed to have the best collection of Napoleonic memorabilia outside France, was regarded as an authority on Napoleonic history. He wrote two volumes on Napoleon and the War (1915, 1917). Historical works include Watch the Pacific (Defenceless Australia) (1924) and Pacific Peril (or Menace of Japan's Mandated Islands) (1933).
In 1924 Marks married Linda Wallis, second daughter of Charles Leicester Wallis, one of the founders of Winchcombe Carson and Company. He and his family were living in Bondi at the time of his death.
