Bradley was working as a boiler maker at the Wabash Railroad when he was encouraged by his Sunday school teacher at Central Christian Church in Moberly to take the entrance examination for the U.S. Military Academy at West Point, NY. Bradley had been planning on saving his money to enter the University of Missouri in Columbia, where he intended to study law. He finished second in the West Point placement exams at Jefferson Barracks Military Post in St. Louis. The first place winner was unable to accept the Congressional appointment, deferring instead to Bradley. While at the academy, Bradley's focus on sports prevented him from excelling academically. He was a baseball star, though, and often played on semi-pro teams for no remuneration (to ensure his eligibility to represent the academy). He was considered one of the most outstanding college players in the nation his junior and senior seasons at West Point, noted as both a power hitter and an outfielder with one of the best arms in his day. While at West Point, Bradley joined the local Masonic Lodge in Highland Falls, New York.

Bradley's first wife, Mary Quayle, grew up across the street from him in Moberly. The pair attended Central Christian Church and Moberly High School together. Moberly called Bradley its favorite son and throughout his life Bradley called Moberly his hometown and his favorite city in the world. He was a frequent visitor to Moberly throughout his career, was a member of the Moberly Rotary Club, played near handicap golf regularly at the local course and had a "Bradley pew" at Central Christian Church. When a flag project opened in 2009 in the Moberly cemetery, General Bradley and his first son - in - law and West Point graduate, the late Major Henry Shaw Bukema, were memorialized with flags in their honor from grateful citizens.

At West Point Bradley lettered in baseball three times, including the 1914 team, from which every player remaining in the army became a general. He graduated from West Point in 1915 as part of a class that contained many future generals, and which military historians have called "the class the stars fell on". There were ultimately 59 generals in that graduating class, with Bradley and Dwight Eisenhower attaining the rank of General of the Army.

Bradley was commissioned into the infantry and was first assigned to the 14th Infantry Regiment. He served on the U.S. - Mexico border in 1915. When war was declared, he was promoted to captain and sent to guard the Butte, Montana, copper mines.

Bradley joined the 19th Infantry Division in August 1918, which was scheduled for European deployment, but the influenza pandemic and the armistice prevented it.

Between the wars, he taught and studied. From 1920 – 24, he taught mathematics at West Point. He was promoted to major in 1924 and took the advanced infantry course at Fort Benning, Georgia. After a brief service in Hawaii, he studied at the Command and General Staff School at Fort Leavenworth in 1928 – 29. From 1929, he taught at West Point again, taking a break to study at the Army War College in 1934. He was promoted to lieutenant colonel in 1936 and worked at the War Department; after 1938 he was directly under Army Chief of Staff George Marshall. In February 1941, he was promoted to brigadier general (bypassing the rank of colonel) and sent to command Fort Benning (the first from his class to become a general officer). In February 1942, he took command of the 82nd Infantry Division before being switched to the 28th Infantry Division in June.

Bradley did not receive a front line command until early 1943, after Operation Torch. He had been given VIII Corps, but instead was sent to North Africa to be Eisenhower's front line troubleshooter. At Bradley's suggestion, II Corps, which had just suffered the devastating loss at the Kasserine Pass, was overhauled from top to bottom, and Eisenhower installed George S. Patton as corps commander. Patton requested Bradley as his deputy, but Bradley retained the right to represent Eisenhower as well.

Bradley succeeded Patton as head of II Corps in April and directed it in the final Tunisian battles of April and May. Promoted to the rank of lieutenant general, Bradley commanded the Second Corps in the invasion of Sicily.

Bradley moved to London as commander in chief of the American ground forces preparing to invade France in 1944. For D-Day, Bradley was chosen to command the US 1st Army, which alongside the British Second Army made up General Montgomery's 21st Army Group.

On 10 June, General Bradley and his staff debarked to establish a headquarters ashore. During Operation Overlord, he commanded three corps directed at the two American invasion targets, Utah Beach and Omaha Beach. Later in July, he planned Operation Cobra, the beginning of the breakout from the Normandy beachhead. Operation Cobra called for the use of strategic bombers using huge bomb loads to attack German defensive lines. After several postponements due to weather, the operation began on July 25, 1944 with a short, very intensive bombardment with lighter explosives, designed so as not to create greater rubble and craters that would slow Allied progress. Unfortunately, Bradley's failure to properly coordinate attack plans with strategic bombing forces resulted in hundreds of American casualties, including the death of a field officer, General Lesley McNair. However, the bombing was successful in knocking out the German communication system, leading to confusion and ineffectiveness, and opened the way for the ground offensive by attacking infantry. Bradley sent in three infantry divisions — the 9th, 4th and 30th — to move in close behind the bombing. The infantry succeeded in cracking the German defenses, opening the way for advances by armored forces commanded by General Patton to sweep around the German lines.

As the build-up continued in Normandy, the 3rd Army was formed under Patton, Bradley's former commander, while General Hodges succeeded Bradley in command of the 1st Army; together, they made up Bradley's new command, the 12th Army Group. By August, the 12th Army Group had swollen to over 900,000 men and ultimately consisted of four field armies. It was the largest group of American soldiers to ever serve under one field commander.

An opportunity for trapping an entire German Army Group in northern France was created after Hitler refused to allow his army to flee rapidly advancing Allied pincer movements. After the German attempt to split the US armies at Mortain (Operation Lüttich), Bradley's Army Group and XV Corps became the southern pincer in forming the Falaise Pocket, trapping the German Seventh Army and Fifth Panzer Army in Normandy. The northern pincer was formed of Canadian forces, part of British General Sir Bernard L. Montgomery's 21 Army Group. On August 13, 1944, concerned that American troops would clash with Canadian forces advancing from the north - west, Bradley overrode Patton's orders for a further push north towards Falaise, while ordering XV Corps to 'concentrate for operations in another direction'. Any American troops in the vicinity of Argentan were ordered to be withdrawn. This order effectively halted the southern pincer movement of General Haislip's XV Corps. Though General Patton protested the order, he obeyed it, leaving an exit - a 'trap with a gap' - for the remaining German forces. Around 20 - 50,000 German troops (leaving almost all of their heavy material) escaped through the gap, avoiding encirclement and almost certain destruction. They would later be reorganized and rearmed in time to slow the Allied advance into Holland and Germany. Most of the blame for this outcome has been placed on Bradley. Bradley had incorrectly assumed, based on Ultra decoding transcripts, that most of the Germans had already escaped encirclement, and he feared a German counterattack as well as possible friendly fire casualties. Though admitting a mistake had been made, Bradley placed the blame on General Montgomery for moving the Commonwealth troops too slowly, though the latter were in direct contact with a large number of SS Panzer, Fallschirmjaeger, and other elite German forces.
 
The American forces reached the 'Siegfried Line' or 'Westwall' in late September. The success of the advance had taken the Allied high command by surprise. They had expected the German Wehrmacht to make stands on the natural defensive lines provided by the French rivers, and had not prepared the logistics for the much deeper advance of the Allied armies, so fuel ran short.

Eisenhower faced a decision on strategy. Bradley favored an advance into the Saarland, or possibly a two thrust assault on both the Saarland and the Ruhr Area. Montgomery argued for a narrow thrust across the Lower Rhine, preferably with all Allied ground forces under his personal command as they had been in the early months of the Normandy campaign, into the open country beyond and then to the northern flank into the Ruhr, thus avoiding the Siegfried Line. Although Montgomery was not permitted to launch an offensive on the scale he had wanted, George Marshall and Hap Arnold were eager to use the First Allied Airborne Army to cross the Rhine, so Eisenhower agreed to Operation Market - Garden. Bradley opposed Operation Market Garden, and bitterly protested to Eisenhower the priority of supplies given to Montgomery, but Eisenhower, mindful of British public opinion regarding damage from V-1 missile launches in the north, refused to make any changes.

Bradley's Army Group now covered a very wide front in hilly country, from the Netherlands to Lorraine. Despite having the largest concentration of Allied army forces, Bradley faced difficulties in prosecuting a successful broad front offensive in difficult country with a skilled enemy. General Bradley and his First Army commander, General Courtney Hodges eventually decided to attack through a corridor known as the Aachen Gap towards the German township of Schmidt. The only nearby military objectives were the Roer River flood control dams, but these were not mentioned in contemporary plans and documents. Bradley and Hodges' original objective may have been to outflank German forces and prevent them from reinforcing their units further north in the Battle of Aachen. After the war, Bradley would cite the Roer dams as the objective. Since the Germans held the dams, they could also unleash millions of gallons of water into the path of advance. The campaign's confused objectives, combined with poor intelligence resulted in the costly series of battles known as the Battle of Hurtgen Forest, which cost some 33,000 American casualties. At the end of the fighting in the Hurtgen, German forces remained in control of the Roer dams in what has been described as "the most ineptly fought series of battles of the war in the west." Further south, Patton's Third Army, which had been advancing with great speed, was faced with last priority (behind the U.S. First and Ninth Armies) for supplies, gasoline and ammunition. As a result, the Third Army lost momentum as German resistance stiffened around the extensive defenses surrounding the city of Metz. While Bradley focused on these two campaigns, the Germans were in the process of assembling troops and materiel for a surprise winter offensive.

Bradley's command took the initial brunt of what would become the Battle of the Bulge. For logistical and command reasons, General Eisenhower decided to place Bradley's 1st and Ninth Armies under the temporary command of Field Marshal Montgomery's 21st Army Group on the northern flank of the Bulge. Bradley was incensed, and began shouting at Eisenhower: "By God, I cannot be responsible to the American people if you do this. I resign." Eisenhower turned red, took a breath and replied evenly "Brad, I - not you, am responsible to the American people. Your resignation therefore means absolutely nothing."." Bradley paused, made one more protest, then fell silent as Eisenhower concluded "Well, Brad, those are my orders." At least one historian has attributed Eisenhower's support for Bradley's subsequent promotion to four star general was based in part on a desire to compensate him for the way in which he had been sidelined during the Battle of the Bulge. Others point out that both Secretary of War Stimson and General Eisenhower had desired to reward General Patton with a fourth star for his string of accomplishments in 1944, but that Eisenhower could not promote Patton over Bradley, Devers, and other senior commanders without upsetting the chain of command.

Bradley used the advantage gained in March 1945 — after Eisenhower authorized a difficult but successful Allied offensive (Operation Veritable and Operation Grenade) in February 1945 — to break the German defenses and cross the Rhine into the industrial heartland of the Ruhr. Aggressive pursuit of the disintegrating German troops by the Ninth Armored Division resulted in the capture of a bridge across the Rhine River at Remagen. Bradley quickly exploited the crossing, forming the southern arm of an enormous pincer movement encircling the German forces in the Ruhr from the north and south. Over 300,000 prisoners were taken. American forces then met up with the Soviet forces near the Elbe River in mid April. By V-E Day, the 12th Army Group was a force of four armies (1st, 3rd, 9th, and 15th) that numbered over 1.3 million men.

Unlike some of the more colorful generals of World War II, Bradley was polite and courteous in his public appearances. A reticent man, Bradley was first favorably brought to public attention by war correspondent Ernie Pyle, who was urged by General Eisenhower to "go and discover Bradley". Pyle subsequently wrote several dispatches in which he referred to Bradley as the GI's general, a title that would stay with Bradley throughout his remaining career. Will Lang Jr. of Life magazine said "The thing I most admire about Omar Bradley is his gentleness. He was never known to issue an order to anybody of any rank without saying 'Please' first."

While the public at large never forgot the image created by newspaper correspondents, a different view of Bradley was offered by combat historian S.L.A. Marshall, who knew both Bradley and George Patton, and had interviewed officers and men under their commands. Marshall, who was also a critic of George S. Patton, noted that Bradley's 'common man' image "was played up by Ernie Pyle... The GI's were not impressed with him. They scarcely knew him. He's not a flamboyant figure and he didn't get out much to troops. And the idea that he was idolized by the average soldier is just rot."

While Bradley retained his reputation as the GI's general, he was criticized by some of his contemporaries for other aspects of his leadership style, sometimes described as 'managerial' in nature. British General Bernard Montgomery's assessment of Bradley was that he was "dull, conscientious, dependable, and loyal". He had a habit of peremptorily relieving senior commanders who he felt were too independent, or whose command style did not agree with his own, such as the colorful and aggressive General Terry Allen, commander of the U.S. 1st Infantry Division. While Patton is often viewed today as the prototype of the intolerant, impulsive commander, Bradley actually sacked far more generals and senior commanders during World War II, whereas Patton relieved only one general from his command - Orlando Ward - for cause during the entire war (and only after giving General Ward two warnings).

President Truman appointed Bradley to head the Veterans Administration for two years after the war. He is credited with doing much to improve its health care system and with helping veterans receive their educational benefits under the G.I. Bill of Rights. Bradley's influence on the VA is credited with helping shape it into the agency it is today. He was a regular visitor to Capitol Hill and lobbied on behalf of veterans' benefits in testimony before various congressional veteran affairs committees.

Bradley became the Army Chief of Staff in 1948. After assuming command, Bradley found a U.S. military establishment badly in need of reorganization, equipment, and training. As Bradley himself put it, "the Army of 1948 could not fight its way out of a paper bag."

On August 11, 1949, President Harry S Truman appointed Bradley the first Chairman of the Joint Chiefs of Staff. After his initial 1948 plan to expand the Army and modernize its equipment was rejected by the Truman Administration, Bradley reacted to the increasingly severe postwar defense department budget cutbacks imposed by Secretary of Defense Louis A. Johnson by publicly supporting Johnson's decisions, going so far as to tell Congress that he would be doing a "disservice to the nation" if he asked for a larger military force. Bradley also suggested that official Navy protests of Secretary Johnson's actions in cancelling construction of its supercarrier, the USS United States were due to improper personal or political, even mutinous motives, calling Navy admirals "fancy dans who won't hit the line with all they have on every play unless they can call the signals", and who were in "open rebellion against the civilian control."

In his second memoir, Bradley would later state that not arguing more forcefully in 1948 and 1949 for a sufficient defense department budget "was a mistake... perhaps the greatest mistake I made in my postwar years in Washington."

On September 22, 1950, he was promoted to the rank of General of the Army, the fifth — and last — man to achieve that rank. That same year, Bradley was made the first Chairman of the NATO Military Committee. He remained on the committee until August 1953, when he left active duty. During his service, Bradley visited the White House over 300 times and was frequently featured on the cover of TIME magazine.

As Chairman of the Joint Chiefs of Staff, Bradley was the senior military commander at the outset of the Korean War. When North Korea invaded South Korea in June 1950, Bradley was faced with re-organizing and deploying an American military force that was a shadow of its World War II counterpart. The impact of the Truman administration's defense budget cutbacks were now keenly felt, as poorly equipped American troops, lacking sufficient tanks, anti - tank weapons, or artillery were driven down the Korean peninsula to Pusan in a series of costly rearguard actions. In a postwar analysis of the unpreparedness of U.S. Army forces deployed to Korea during the summer and fall of 1950, Army Major General Floyd L. Parks stated that "Many who never lived to tell the tale had to fight the full range of ground warfare from offensive to delaying action, unit by unit, man by man... [T]hat we were able to snatch victory from the jaws of defeat... does not relieve us from the blame of having placed our own flesh and blood in such a predicament."

Bradley was the chief military policy maker during the Korean War, and supported Truman's original plan of 'rolling back' Communist aggression by conquering all of North Korea. When Chinese Communists entered North Korea in late 1950 and again drove back American forces, Bradley agreed that rollback had to be dropped in favor of a containment strategy of North Korea. The containment strategy was subsequently adopted by the Truman administration for North Korea, and applied to communist expansion worldwide. Never an admirer of General Douglas MacArthur, Bradley was instrumental in convincing Truman to dismiss MacArthur as the overall commander in the Korean theatre after MacArthur resisted administration attempts to scale back strategic objectives in the Korean conflict.

In testimony to Congress Bradley strongly rebuked MacArthur for his support of victory at all costs in Korea. Soon after Truman relieved MacArthur of command in April 1951, Bradley said in Congressional testimony, "Red China is not the powerful nation seeking to dominate the world. Frankly, in the opinion of the Joint Chiefs of Staff, this strategy would involve us in the wrong war, at the wrong place, at the wrong time, and with the wrong enemy."

In retirement Bradley held a number of positions in commercial life, among them Chairman of the Board of the Bulova Watch Company from 1958 to 1973.

His memoirs, A Soldier's Story (ghostwritten by A.J. Liebling), appeared in 1951; a fuller autobiography A General's Life: An Autobiography (coauthored by Clay Blair) appeared in 1983. He took the opportunity to attack Field Marshal Montgomery's 1945 claims to have won the Battle of the Bulge. Bradley spent his last years in Texas at a special residence on the grounds of the William Beaumont Army Medical Center, part of the complex which supports Fort Bliss.

On December 1, 1965, Bradley's wife, Mary, died of leukemia. He met Esther Dora "Kitty" Buhler and married her on September 12, 1966; they were married until his death.

As a horse racing fan, Bradley spent much of his leisure time at racetracks in California and often presented the winners trophies. He also was a lifetime sports fan, especially of college football. He was the 1948 Grand Marshal of the Tournament of Roses and attended several subsequent Rose Bowl games (his black limousine with personalized CA license plate "ONB" and a red plate with 5 gold stars was frequently seen driving through Pasadena streets with police motorcycle escort toward the Rose Bowl on New Year's Day), and was prominent at the Sun Bowl in El Paso, Texas, and the Independence Bowl in Shreveport, Louisiana, in later years.

Bradley also served as a member of President Lyndon Johnson's Wise Men, a high level advisory group considering policy for the Vietnam War. Bradley was a hawk and recommended against withdrawal from Vietnam.

In 1970, Bradley served as a consultant for the film Patton, though the extent of his active participation is largely unknown. Screenwriters Francis Ford Coppola and Edmund H. North wrote most of the film based on two biographies, Bradley's A Soldier's Story and Patton: Ordeal and Triumph by Ladislas Farago. As the film was made without access to General Patton's diaries or any information from his family, it largely relied upon observations by Bradley and other military contemporaries when attempting to reconstruct Patton's thoughts and motives. In a review of the film Patton, S.L.A. Marshall, who knew both Patton and Bradley, stated that "The Bradley name gets heavy billing on a picture of [a] comrade that, while not caricature, is the likeness of a victorious, glory - seeking buffoon... Patton in the flesh was an enigma. He so stays in the film... Napoleon once said that the art of the general is not strategy but knowing how to mold human nature... Maybe that is all producer Frank McCarthy and Gen. Bradley, his chief advisor, are trying to say." While Bradley knew Patton personally, it was also well known that the two men were polar opposites in personality, and that Bradley despised Patton both personally and professionally. Bradley's role in the film remains controversial to this day.

Bradley attended the 30th anniversary of D-Day at Normandy, France on June 6, 1974, participating in various parades.

On January 10, 1977, Bradley was presented with the Presidential Medal of Freedom by President Gerald Ford.

One of Bradley's last public appearances was at the festivities surrounding the inauguration of President Ronald Reagan in January 1981.

Omar Bradley died on April 8, 1981 in New York City of a cardiac arrhythmia, just a few minutes after receiving an award from the National Institute of Social Sciences. He is buried at Arlington National Cemetery, next to his two wives.

Bradley's posthumous autobiography, A General's Life, was published in 1983; the book was begun by Bradley himself, who found writing difficult, and so Clay Blair was brought in to help shape the autobiography; after Bradley's death, Blair continued the writing, making the unusual choice of using Bradley's first person voice. The resulting book is highly readable, and based on extremely thorough research, including extensive interviews with all concerned, and Bradley's own papers.

Bradley is known for saying, "Ours is a world of nuclear giants and ethical infants. We know more about war than about peace, more about killing than we know about living."

The U.S. Army's M2 Bradley infantry fighting vehicle and M3 Bradley cavalry fighting vehicle are named after General Bradley.

Bradley's hometown, Moberly, Missouri, is planning a library and museum in his honor. Two recent Bradley Leadership Symposia in Moberly have honored his role as one of the American military's foremost teachers of young officers. On February 12, 2010, the U.S. House of Representatives, the Missouri Senate, the Missouri House, the County of Randolph and the City of Moberly all recognized Bradley's birthday as General Omar Nelson Bradley Day. The ceremony marking the day was held at his high school alma mater and featured addresses by the current Congressional representative, Blaine Luetkemeyer, and Moberly High School Principal Aaron Vitt.

On May 5, 2000, the United States Postal Service issued a series of Distinguished Soldiers stamps in which Bradley was honored.