Churchill's four volume epic, A History of the English-Speaking Peoples, was published between 1956 and 1958.  The work traces a sweeping historical arc from Roman Britain through the end of the Nineteenth Century.  Volumes I & II deal primarily with Britain and her rise to become a world power, including early colonization of North America.  Volume III necessarily broadens in scope, covering 1668 to 1815, including the American Revolution and the defeat of Napoleon.  Volume IV covers 85 years of the Nineteenth Century, ending with the death of Queen Victoria.  Perhaps not conincidentally, this is the very year that saw Churchill conclude his first North American lecture tour, take his first seat in Parliament, and begin to make history himself.
The work itself was two decades in the making.  The Churchillian conceptions that underpinnned it were lifelong.
Churchill began A History of the English-Speaking Peoples in the 1930s, completing a draft of "about half a million words" which was set aside when Churchill returned to the Admiralty and to war in September 1939.  The work was fittingly interrupted by an unprecedented alliance among the English-speaking peoples during the Second World War - an alliance Churchill personally did much to cultivate, cement, and sustain.  The interruption continued as Churchill bent his literary efforts to his six-volume history, The Second World War, and then his remaining political energies to his second and final premiership from 1951-1955.