During the Second World War, the 1st Battalion, Royal Welch Fusiliers was a Regular Army unit and part of the 6th Infantry Brigade, assigned to the 2nd Infantry Division. It served in France in 1940 with the British Expeditionary Force. The battalion fought in the short but fierce battles of France and Belgium and was forced to retreat and be evacuated during the Dunkirk evacuation. After two years spent in the United Kingdom, waiting and preparing for the invasion that never came (Operation Sea Lion), the 1st RWF and the rest of 2nd Division were sent to British India to fight the Imperial Japanese Army after a string of defeats inflicted upon the British and Indian troops. The battalion was involved in the Burma Campaign, particularly the Battle of Kohima, nicknamed "Stalingrad of the East" due to the ferocity of fighting on both sides, that helped to turn the tide of the campaign in the South East Asian theatre.