After escaping and making his way to Palestine (for which he was awarded the Military Cross), he served with the 2nd Battalion, Cameron Highlanders, and served with the battalion until August 1941. He returned to the United Kingdom and, eventually, went on to be Commanding officer (CO) of the 5th Battalion, Queen's Own Cameron Highlanders from July 1944. The battalion was a TA unit formed in 1939 as a second line duplicate of the 4th Battalion and now formed part of the 152nd Brigade, commanded by Brigadier James Cassels, of Major General Tom Rennie's 51st (Highland) Division. Both the original brigade and division had been captured, as had Lang himself, in France in June 1940 but had been reformed that August by redesignating the 9th (Highland) Infantry Division and, after having served in North Africa and Sicily, were now fighting in Normandy in the aftermath of the D-Day landings. Lang was to command the 5th Cameron Highlanders throughout the rest of the campaign in Northwest Europe until Victory in Europe Day (VE Day) in May 1945. He was awarded the Distinguished Service Order for his leadership of the battalion in 1944.