In 1939 he enlisted in the
Territorial Army, part of the
British Army, in the 4th Battalion,
Green Howards. At the outbreak of the
Second World War he was
mobilised and transferred to the 6th Battalion, Green Howards, and went to France as part of the
British Expeditionary Force in 1940, where he served as the commanding officer's despatch rider. He was promoted from lance corporal to sergeant during the
evacuation from Dunkirk. He then fought from
El Alamein to
Tunis as part of the
British Eighth Army in the
North African Campaign. He was made
company sergeant major shortly before the
invasion of Sicily in 1943, where he was wounded at the battle of
Primosole Bridge. On D-Day, the 6th Green Howards landed on
Gold Beach. As his company moved inland from the beaches after the initial landings, Hollis went with his company commander to investigate two German
pillboxes which had been by-passed. He rushed the first, taking all but five of the occupants prisoner; and then dealt with the second, taking 26 prisoners. He next cleared a neighbouring trench. Later that day, he led an unsuccessful attack on an enemy position containing a field gun and multiple
MG 42 machine guns. After withdrawing, he learned that two of his men had been left behind. He said to his commanding officer, Major Lofthouse, "I took them in. I will try to get them out." In September 1944 he was wounded in the leg and evacuated to England, where he was decorated by
King George VI on 10 October 1944.
Citation The citation published in the London Gazette read: ==Later life==