A careful evaluation of diaries and memoirs of British temporary officers in World War I suggests that the class consciousness and Regular Army ideals inculcated during training had little bearing on officers’ actual experiences on the front lines. Their accounts confirm previous scholars’ conclusions about the presence of class feelings among officers, but the value they place on military effectiveness in the trenches is much more significant. After 1914, high casualty rates among junior officers forced the British army to seek candidates for commissions from social classes that, before the war, would not have been considered officer material. Accounts from both the traditional officer class and from the working class reveal new officers’ conscious attempts, encouraged by their superiors, to conform to the pre-war Regular Army ideal of the “officer and gentleman.” These attempts, as well as the very existence of the term “temporary gentleman,” demonstrate the new officers’ consciousness of their artificial elevation to the status of gentlemen. But the diaries and memoirs reveal that, on the front lines, an “efficient” officer was highly valued, whatever his social background