Edited sentence: And Churchill's books were put together collaboratively, as he actively solicited others involved in the war for the papers and remembrances while writing the books.Deficiencies in the Churchill accounts are largely due to the lack of still secret Ultra intelligence, as historian John Keegan notes in his 1985 introduction to the series.Keegan also notes the uniqueness of Churchill's account, since neither Roosevelt, Stalin and Hitler wrote any first-hand accounts of the war