General John Crocker in France 1944

Lieutenant General John Crocker, Commander of 1st Corps, in France, August 1944. Sir John Tredinnick Crocker, GCB, KBE, DSO, MC (4 January 1896 - 9 March 1963) was not much of a talker and he was a lousy self-promoter because of it. Yet he was one of the most important British soldiers of the Second World War, commanding a corps in North Africa and subsequently being assigned “the most ambitious, the most difficult and the most important task” of any Allied corps commander during Operation Overlord. His influence was not limited to the period of the war either. He was intimately involved with the development of British armoured forces during the 1920s and 1930s, and after the war he oversaw the production of the doctrine and training publications that would guide the British Army for much of the Cold War. He also served as Commander-in-Chief Middle East Land Forces, and he finished his career as Adjutant-General to the Forces. Field Marshal Montgomery would have preferred it if Crocker had retired as Chief of the Imperial General Staff (CIGS), but in 1949 Prime Minister Clement Atlee chose Sir William Slim for the post instead. By almost any standard, Crocker had a very successful army career. So, how did someone so quiet achieve so much? Crocker’s influence, and his rise in the British Army, rested squarely on a foundation of technical competence and unimpeachable integrity. These were also the qualities that underpinned his method of command. A keenly intelligent man, Crocker found himself in high demand whenever there were problems to be solved, whether they concerned testing the abilities of tanks, building an armoured formation, or sequencing an amphibious assault. He had excelled at staff college and at just about everything else he had tackled during the interwar period, so it is no wonder that he attracted the attention of people like Alan Brooke and Percy Hobart. They trusted him, and not just for his technical ability. His Great War record had shown him to be completely composed under fire, and his reputation for being straight with everyone, whether they wanted to hear what he had to say or not, had earned him the nickname “Honest John.” In 1935, Hobart wrote that Crocker was “trusted by me and by all ranks of the Tank Brigade ... his patience, tact and integrity have won him affection.” There was also an understated determination about Crocker. During tough times like the battles for Caen, he could grit his teeth and drive on to his objectives, even when the fighting was tough and the casualty count high. That steely resolve faded for a while when he suffered the agonizing loss of his only son, Wilfrid, in October 1944, but his skills and his quiet nobility never left him.

Source :
"Corps Commanders: Five British and Canadian Generals at War, 1939-45" by Douglas E. Delaney 
https://en.wikipedia.org/wiki/John_Crocker