In a specially arranged meeting with President Dwight D. Eisenhower, Army officer Martin Maher complains that the United States Military Academy at West Point, where he has served for fifty years, is forcing him into retirement. Protesting that he is perfectly healthy, Marty remembers his first day at the Academy: Having just arrived from County Tipperary, Ireland, Marty reports to West Point to begin his job as a waiter. Unimpressed with military discipline, and too much the exuberant Irishman to maintain a silent and respectful demeanor, Marty gets himself into trouble from the very beginning. His salary proves insufficient to pay for the dishes he constantly breaks, and when he realizes that enlisted men receive better treatment than do hired laborers, he immediately joins up. Mistakenly believing that Corp. Rudolph Heinz betrayed a cadet, Marty fights the officer, and is placed in the guardhouse. Upon his release, he learns that Capt. Herman J. Koehler was impressed with his boxing skills and wants him to assist in athletics instruction. Soon after Marty begins teaching boxing classes, he meets Mrs. Koehler's cook, Mary O'Donnell, an attractive young woman who has just arrived from County Donegal. It is love at first sight for Marty, but Mary refuses to speak to him. Exasperated, Marty finally proposes and is astonished when Mary says yes. Capt. Koehler, she explains, had advised her to remain silent because to speak to an argumentative Irishman would have invited an immediate fight. The two do fight but are married nonetheless. Over the following few years, Marty becomes a corporal, and Mary saves enough money to bring his father and brother Dinny to America. Dinny becomes a successful businessman, and although Mary loves West Point, Marty decides to quit the military and join his brother's firm. When Mary becomes pregnant, however, he re-enlists. The baby, named Martin Maher, III, dies only hours after his birth, and Mary learns that she may never have another child. The cadets, who cherish the couple's friendship, remain with them during their grief. One of these cadets is James "Red" Sundstrom, who worries that he will be dismissed because of his poor grades. Marty and Mary introduce him to Kitty Carter, who tutors Red and, after several years, becomes his bride. As time passes, Marty continues to earn the love and respect of cadets such as Omar Bradley, James Van Fleet, George Patton and Eisenhower. When the U.S. enters the war in 1917, both Marty and his father try to join the troops at the front, but Koehler, now a colonel, argues that they are needed at the Academy. Soon after the armistice is signed, Marty hears that Red has been killed, and in pain and disgust, he again decides to leave the Academy. Kitty receives Red's posthumously awarded medal of honor, along with an honorary West Point appointment for her baby son. When she reacts with bitterness, it is Marty who reminds her how important military service was to Red. Years later, Marty is still at West Point, and James "Red" Sundstrom, Jr., along with the sons of others whom Marty had trained, is becoming a cadet. News of Japan's attack on Pearl Harbor is announced, whereupon Red, Jr. makes a confession to Marty: He has broken the Academy's code of honor by secretly marrying and then having the marriage annulled. Because Red, Jr. is like a son to her, Mary begs Marty to keep quiet about the incident, but the breach of honor so disturbs him that he decides to retire. During their conversation, Red, Jr. and Kitty arrive. Red, Jr. has resigned from the Academy, enlisted in the Army, and is being shipped overseas. Beaming with pride, Marty watches him depart. Later, Mary attempts to view one of the parades she so loves, but her health is too poor and she is forced to watch the proceedings from her own porch. As Marty is fetching her shawl, she quietly dies. On Christmas Eve, Marty returns home alone. He begins to prepare a poor supper for himself but is interrupted by a group of lively cadets. Suddenly Kitty arrives with Red, Jr., who has earned his captain's bars on the battlefield and wants Marty to pin them on. By Eisenhower's desk, Marty completes his reminiscences, adding that West Point "has been my whole life." Eisenhower contacts West Point, and when Marty returns to the Academy, the cadets arrange for a full dress parade in his honor. As the band plays a series of Irish tunes, all the people Marty loves, both living and dead, join the marching cadets on the field.