Upham was intent on learning the essentials of fighting and becoming skilled in using the bayonet, machine gun and grenade. He showed no inclination for the parade ground, where he was well known for making a bungle of any drill, or respect for army conventions or rank. His intolerance of anything not directly of benefit to the war and his forthright, outspoken nature often led him to disagree bluntly with superior officers. Despite his insubordination and impatience to fight, in July 1940 Upham was persuaded to join an OCTU. Due to his outspoken opinions and his tendency to question almost everything, however, he was highly unpopular with the British officers. Upham was particularly critical of the lack of consideration that was given to the problems caused by tanks and aircraft, and felt that the tactics being used relied too much on the methods that had been successful in the First World War. As a result he was placed last in his course, but was commissioned as a second-lieutenant in November 1940.