 He subsequently moved to Du Pont headquarters, first as manager of process development for the Organic Chemicals business, and later as assistant director of the Development Department.After a brief leave for government service - as deputy director and then director of the Chemical, Rubber, and Forest Products Bureau of the National Production Authority - Holbrook resumed his prior Du Pont work but also chaired Du Pont's Corporate Committee for Educational Fellowships and Grants.In 1955 he was named assistant general manager of the Organic Chemicals Department, and in 1957 general manager of the Elastomer Chemicals Department.