The Overseas Military Forces of Canada recognized Barker as "holding the record for fighting decorations" awarded in the First World War. Most decorated hero Barker returned to Canada in May 1919 as the most decorated Canadian of the war, with the Victoria Cross, the Distinguished Service Order and Bar, the Military Cross and two Bars, two Italian Silver Medals for Military Valour, and the French Croix de guerre. He was also mentioned in despatches three times. The Canadian Daily Record, a publication of the Overseas Military Forces of Canada, wrote in December 1918 that William Barker of Dauphin, Manitoba was the Canadian holding the record for "most fighting decorations" in the war. No other Canadian soldier, sailor or airman has surpassed this record, and the Canadian War Museum exhibit, located in Ottawa, Ontario, states: "Lieutenant Colonel William G. Barker, one of the legendary aces of the war, remains the most decorated Canadian in military service." A plaque on his tomb in the mausoleum of Toronto's Mount Pleasant Cemetery, officially unveiled on 22 September 2011, describes him as "The most decorated war hero in the history of Canada, the British Empire, and the Commonwealth of Nations." Only two other servicemen in the history of the Commonwealth or Empire have received as many British medals for gallantry. These were Mick Mannock and James McCudden and, like Barker, both were "scout pilots" in the First World War. Barker, Mannock, and McCudden each received six British medals, including the Victoria Cross. McCudden was also awarded a French Croix de Guerre. But with his three foreign medals and three Mentions in Despatches, Barker received a total of 12 awards for valor. Post-war Barker formed a business partnership, Bishop-Barker Aeroplanes Limited, with fellow Victoria Cross recipient and Canadian ace Billy Bishop which lasted for about three years. In 1922 he rejoined the fledgling Canadian Air Force in the rank of Wing Commander, serving as the Station Commander of Camp Borden from 1922 to 1924. Barker was appointed acting director of the RCAF in early 1924 and he graduated from RAF Staff College, Andover, in 1926. While waiting to start RAF Staff College Course No 4, Barker spent two weeks in Iraq with the RAF to learn more about the uses of airpower. He formally reported on his findings to the Minister of National Defence, and informally to Brigadier General Billy Mitchell, of the US Air Service.