Heart of the Matter provides one of the most unique examinations of World War II in that it is experienced through the eyes of a major oil company, and the oil industry in general. Phillips Petroleum''s wartime activities have been broken down into four major areas: research and development of oil technology as it affected Allied armies in the field; conservation programs that affected the ability to industrially and financially support the Allies; manpower and labor issues as women filled the void left by men in military service; and the politics and diplomacy of securing and expanding oil supplies while waging war. How important was oil? After the war, Commander-in-Chief of the American Pacific Fleet Admiral Chester W. Nimitz stated, "Oil and oil products constituted more than twice the combined tonnage of all other supplies shipped overseas, including men, weapons, ammunition, and food." Uncovering the wartime activities of Phillips 66 provides a fascinating account of the depths to which the American oil industry dove to ensure victory over the Axis powers.