In 1930 he wrote his first autobiography, My Early Life, after which he began his researches for Marlborough: His Life and Times (1933–38), a four-volume biography of his ancestor, John Churchill, 1st Duke of Marlborough.
Pada tahun 1930, ia menulis otobiografi pertamanya, My Early Life, setelah itu ia memulai risetnya untuk Marlborough: His Life and Times (1933–38), sebuah buku biografi empat volume tentang leluhurnya, John Churchill, 1st Duke of Marlborough.