With the advent of the U.S. involvement in World War II, Harris' group began advising the Army Quartermaster about textiles, as well as helping to solve a myriad of problems for the National Bureau of Standards. George Dorio, a Frenchman from the Harvard Business School, was recruited to run the Research and Development Branch of the Office of the Quartermaster General. According to Harris, Colonel Dorio called him one Sunday morning and immediately requested his presence at the Pentagon. Upon Harris' arrival, Colonel Dorio pulled out some cotton underwear from a box. Almost immediately the underwear disintegrated. Colonel Dorio wanted to know why this had occurred. They soon found out that the cotton which comprised the garment had been treated with chemicals against gas warfare, and in the process hydrochloric acid had been liberated which led to the deterioration of the fabric. Since Harris had already been working on the degradation of cellulose by various methods, Dorio had him start work on this new project the next day.
Another military stumbling block that Harris' group worked on was the development of a shrink-proofing process to alleviate the difficulty of laundering soldier's uniforms in the field. They also made great strides in the prevention of rotting sandbag and tent materials, as well as determining why electrical equipment kept shorting out in the South Pacific. The importance of shrink-proofing is evident in that, simply from not having to replace items such as socks and underwear, the Army saved approximately $1,500,000 per month during World War II. Harris also studied the dispersal of water vapor through fabric, and determined that water vapor passed through tightly woven and loosely woven clothing with equal rapidity, neglecting appreciable wind. With this information in hand, tropical uniforms of soldiers were redesigned with thin, tightly woven material, greatly improving the efficiency and morale of the soldiers.