and by forgoing participation in events where his difficulty in hearing would pose an obstacle, such as large conferences. By the late 1930s, he worried that his hearing condition might result in his mandatory retirement for medical reasons. Instead, Marshall issued a waiver which allowed him to continue to serve. His hearing loss may have prevented him from obtaining a field command during World War II, but Marshall was unwilling to do without his abilities as an organizer and trainer. Legacy Reputation McNair was held in high regard by his contemporaries, as evidenced by performance appraisals that routinely gave him the highest possible ratings. Marshall also held McNair in high esteem, as demonstrated by the fact that McNair was a top stateside commander during World War II, was considered for a top command in Europe, and was ultimately selected to command the First United States Army Group as part of a deception plan that required a general with a good reputation and high name recognition for successful execution. In addition, soon after McNair was assigned to serve as commandant of the Command and General Staff School, Marshall learned that he would become the Chief of Staff of the Army. In a letter to McNair, Marshall wrote: "You at the head of Leavenworth are one of the great satisfactions I have at the moment in visualizing the responsibilities of the next couple of years." Mark W. Clark served under McNair as operations officer (G-3) at AGF Headquarters before ascending to the general officer ranks. In his autobiography, Clark referred to McNair as "one of the most brilliant, selfless and devoted soldiers" he had ever encountered. McNair's primary legacy was his role as "the brains of the Army", in that his involvement in unit design (the triangular division), education (the Command and General Staff Officer Course), doctrine (updating the Field Service Manual and revising field artillery methods and procedures), weapons design and procurement (experimentation with field artillery, anti-tank weapons, and anti-aircraft weapons), and training of soldiers and units (as commander of Army Ground Forces), especially in the era between World Wars I and II, made him one of the primary architects of the Army as the United States employed it for World War II. Another enduring McNair legacy was his training method of beginning with basic soldier skills and then building through successive echelons until large units became proficient during exercises and