During World War I, Brownell served as an enlisted man and officer, first in the United States Army, then the U.S. Navy.
Initially, he was a lecturer in editorial writing and journalism, but soon began teaching courses in contemporary thought and philosophy.
Brownell’s course in Contemporary Thought, one of the first of its kind in the United States, was intended to help students organize fragments of their educational experience into an intelligible whole.
It consisted of weekly lectures by prominent individuals with expertise in natural sciences, biology, psychology, sociology, history, economics, art, religion and philosophy.
In 1926, Brownell published The New Universe, which enumerated his beliefs, and in 1929 he edited a twelve volume series entitle Man and His World, which included 60 lectures that had been given in his Contemporary Thought course.
As a supervising editor for Harper & Brothers during the 1940s, he edited several books that were designed to integrate various fields of specialized knowledge.
Among his trips were a tour of the Galapagos Islands and an expedition to Cocos Island as the guest of his friend Commander E.F. MacDonald Jr., the Chairman of the Zenith Corporation; a six-month sojourn in the interior of Guatemala; a summer in Tahiti; a trip to Isle Royale, Michigan, as a member of the Isle Royale Archeological Expedition; and various cruises in the Caribbean.
Supported by grants from the Rockefeller Foundation and Northwestern University, Brownell continued his community service work in other areas until 1951.
After fully retiring from academic and administrative work in 1954, Brownell spent the remaining years of his life in Fairhope, Alabama.