In 1918, towards the end of World War One, tens of thousands of foreign troops, Americans and British among them, were ordered to Russia in what became known as the Allied Intervention. Winston Churchill saw the foreign troops as anti-Communists, on a crusade to “strangle at birth the Bolshevik State". Lucy Ash travels to the Arctic port of Archangel to look for evidence of a conflict which took place a century ago and transformed Russia's relations with the West for decades to come.