His career is contrasted with that of another soldier, Courtney Massengale, who has no honor, no concern for his troops, and rises in rank through staff positions by cunning and political connections.

This section covers the young Sam Damon's formative years in small town in Nebraska, during which he earns his nickname "The Night Clerk."

Damon's service takes off in World War I, including his battlefield commission by his commanding officer, General Caldwell, and actions, lead to his award of the Medal of Honor.

He meets Major Courtney Massengale, who has his sights set on achieving great success through his military service and with assistance from his Senator uncle, by chance at a cafe.

Sam is demoted back to a 1st Lieutenant upon returning from the war and learns the hard way about the favoritism that plagues the Army (especially for those that graduated from West Point).

The spirit, the heart and, yes, the soul of the officer corps is captured, as are the intangible ambiance and nuances that make up the life of the American soldier and his family.

"[3] General Charles C. Krulak, the commandant of the US Marine Corps, wrote "Once an Eagle has more to teach about leadership – whether it is in the boardroom or on the battlefield – than a score of modern-day management texts.

"[3] Maj. Gen. Robert H. Scales, the commandant of the US Army War College in 1997 wrote on the book's fly-leaf "Once an Eagle has been the literary moral compass for me and my family of soldiers for more than two generations.

"[3] In an interview with Foreign Policy in 2013 however, Scales claimed that the novel's effects damaged the Army's officer corps: "Today’s generation has spent a great deal of time in the field and very little in the classroom or on the staff.

[5] In 1976, NBC created a nine-hour American television miniseries, likewise titled Once An Eagle, based on the book and directed by Richard Michaels and E.W.