The years 1929 to 1939, when Churchill was out of office and out of sympathy with the times, are usually called his Wilderness Years. This lecture suggests they would be better renamed the Marlborough Decade.
John Churchill, Duke of Marlborough was the founder of the family fortunes. In 1929 Winston, who had been born at Blenheim, the great palace given to John as a reward for his victories over Louis XIV, was commissioned to write the biography of his great ancestor. It would take him four volumes and nine years.
The immense advance of £20,000 (four times the then salary of the Prime Minister) steadied his shaky finances. His analysis of the role of Louis XIV, who aspired to absolute power in France and hegemony in Europe, gave him the ideas and the very phrases he would turn against Hitler. Writing the book—whose enormous length and scope made it an industrial enterprise in itself—also perfected the extraordinary work habits he would deploy as wartime Prime Minister and supplied some of the key personnel in the form of his researchers. Specially bound and dedicated copies even served as his calling card to Roosevelt.
In short, the man who won the the Second World War was not Churchill the failed politician but Churchill the author of Marlborough.