In the closing months of the First World War, Britain, America, France and Japan sent arms and 180,000 soldiers to Russia, with the aim of tipping the balance in her post-revolutionary Civil War. From Central Asia to the Arctic and from Poland to the Pacific, they joined anti-Bolshevik forces in trying to overthrow the new men in the Kremlin, in an astonishingly ambitious military adventure known as the Intervention.

Fresh, in the case of the British, from the trenches, they found themselves in a mobile, multi-sided conflict as different as possible from the grim stasis of the Western Front.

Two years later they left again, filing glumly back onto their troopships as port after port fell to the Red Army. Later, American veterans compared the humiliation to Vietnam, and the politicians and generals responsible preferred to trivialise or forget.

Drawing on previously unused diaries, letters and memoirs, A Nasty Little War brings an episode with echoes down the century since vividly to life.