Having given up his first job—teaching—after just one day, Watson took a year’s course in accounting and business at the Miller School of Commerce in Elmira. He left the school in 1891, taking a job at $6 a week as bookkeeper for Clarence Risley’s Market in Painted Post. One year later he joined a traveling salesman, George Cornwell, peddling organs and pianos around the farms for William Bronson’s local hardware store, Watson’s first sales job. When Cornwell left, Watson continued alone, earning $10 per week. After two years of this life, he realized he would be earning $70 per week if he were on a commission. His indignation on making this discovery was such that he quit and moved from his familiar surroundings to the relative metropolis of Buffalo.

Watson had a newly acquired NCR cash register in his butcher shop, for which he had to arrange transfer of the installment payments to the new owner of the butcher shop. On visiting NCR, he met John J. Range and asked him for a job. Determined to join the company, he repeatedly called on Range until, after a number of abortive attempts, he finally was hired in November 1896, as sales apprentice to Range.

In 1912, the company was found guilty of violating the Sherman Antitrust Act. Patterson, Watson, and 26 other NCR executives and managers were convicted for illegal anti-competitive sales practices and were sentenced to one year of imprisonment. Their convictions were unpopular with the public because of the efforts of Patterson and Watson to help those affected by the Dayton, Ohio floods of 1913, but efforts to have them pardoned by President Woodrow Wilson were unsuccessful. However, their convictions were overturned on appeal in 1915 on the grounds that important defense evidence should have been admitted.

Watson married Jeanette Kittredge, from a prominent Dayton, Ohio railroad family, on April 17, 1913. They had two sons and two daughters.

Charles Ranlett Flint who had engineered the amalgamation (via stock acquisition) forming the Computing-Tabulating-Recording Company (CTR) found it difficult to manage the five companies. He hired Watson as general manager on May 1, 1914, when the five companies had about 1,300 employees. Eleven months later he was made President when court cases relating to his time at NCR were resolved. Within four years revenues had been doubled to $9 million. In 1924, he renamed CTR to International Business Machines. Watson built IBM into such a dominant company that the federal government filed a civil antitrust suit against it in 1952. IBM owned and leased to its customers more than 90 percent of all tabulating machines in the United States at the time. When Watson died in 1956, IBM’s revenues were $897 million, and the company had 72,500 employees.

“THINK” – Watson began using “THINK” to motivate, or inspire, staff while at NCR and continued to use it at CTR. International Business Machines’s first U.S. trademark was for the name “THINK” filed as a U.S. trademark on June 6, 1935, with the description “periodical publications”. This trademark was filed fourteen years before the company filed for a U.S. trademark on the name IBM. A biographical article in 1940 noted that “This word is on the most conspicuous wall of every room in every IBM building. Each employee carries a THINK notebook in which to record inspirations. The company stationery, matches, scratch pads all bear the inscription, THINK. A monthly magazine called ‘Think’ is distributed to the employees.” THINK remains a part of IBM’s corporate culture; it was the inspiration behind naming IBM’s successful line of notebook computers, IBM ThinkPad. In 2007, IBM Mid America Employees Federal Credit Union changed its name to Think Mutual Bank.

In 1936 the U.S. Supreme Court upheld a lower court decision that IBM, together with Remington Rand, should cease its practice of requiring its customers to buy their punch cards from it alone. The ruling made little difference because IBM was the only effective supplier to the market, and profits continued undiminished.

Throughout his life, Watson maintained a deep interest in international relations, from both a diplomatic and a business perspective. He was known as President Roosevelt’s unofficial ambassador in New York and often entertained foreign statesmen. In 1937, he was elected president of the International Chamber of Commerce (ICC) and at that year’s biennial congress in Berlin stated the conference keynote to be “World Peace Through World Trade”. That phrase became the slogan of both the ICC and IBM.

Watson’s merger of diplomacy and business was not always lauded. In 1937 Watson met Adolf Hitler in Watson’s capacity as President of the International Chamber of Commerce. During the 1930s, IBM’s German subsidiary was its most profitable foreign operation, and a 2001 book by Edwin Black, IBM and the Holocaust, proves that Watson’s pursuit of profit led him to personally approve and spearhead IBM’s strategic technological relationship with Nazi Germany. It describes how IBM provided the tabulating equipment Hitler used to round up the Jews. His Hollerith punch-card machines are in the Holocaust Museum today. The book describes IBM’s punch cards as “a card with standardized holes”, each representing a different trait of the individual. The card was fed into a “reader” and sorted. Punch cards identified Jews by name. Each one served as “a nineteenth-century bar code for human beings”. In particular, critics point to the Order of the German Eagle medal that Watson received at the Berlin ICC meeting in 1937, as evidence that he was being honored for the help that IBM’s German subsidiary Dehomag (Deutsche Hollerith-Maschinen Gesellschaft mbH) and its punch card machines provided the Nazi regime, particularly in the tabulation of census data (i.e. location of Jews). Another study argues that Watson believed, perhaps naively, that the medal was in recognition of his years of labor on behalf of global commerce and international peace. Within a year of the Berlin congress though, where Watson’s hopes had run high, he found himself strongly protesting the German policy toward the Jews.

In 1937, Watson was awarded the Order of the German Eagle by Adolf Hitler. Watson was also president of the International Chamber of Commerce in 1937; the medal was awarded while the ICC was meeting in Germany that year.

In 1939, he received an honorary degree in Doctor of Commercial Science from Oglethorpe University.

Because of his strong feelings about the issue, Watson wanted to return his German citation shortly after receiving it. When Secretary of State Hull advised him against that course of action, he gave up the idea until the spring of 1940. Then Hull refused advice, and Watson sent the medal back in June 1940. Dehomag’s management disapproved of Watson’s action and considered separating from IBM. This occurred when Germany declared war on the United States in December 1941, and the German shareholders took custody of the Dehomag operation. But during World War II, IBM subsidiaries in occupied Europe never stopped delivery of punch cards to Dehomag, and documents uncovered show that senior executives at IBM world headquarters in New York took great pains to maintain legal authority over Dehomag’s operations and assets through the personal intervention of IBM managers in neutral Switzerland, directed via personal communications and private letters.

In 1941, Watson received the third highest salary and compensation package in the U.S., $517,221, on which he paid 69% in tax.

Since the attribution typically is used to demonstrate the fallacy of predictions, if Watson had made such a prediction in 1943, then, as Gordon Bell pointed out in his ACM 50 years celebration keynote, it would have held true for some ten years.

In the 1940s, Watson was on the national executive board of the Boy Scouts of America and served for a time as an international Scout commissioner. E. Urner Goodman recounts that the elderly Watson attended an international Scout commissioners’ meeting in Switzerland, where the IBM founder asked not to be put on a pedestal. Before the conference was over, Goodman relates, Watson “… sat by that campfire, in Scout uniform, ‘chewing the fat’ like the rest of the boys”. He received the Silver Buffalo Award in 1944. His son, Thomas Jr., later served as national president of the Boy Scouts of America from 1964 to 1968. He was also inducted into the Steuben County (NY) Hall of Fame. Throughout his life Watson continued to own and enjoy the family farm on which he was born. In 1955 he and his wife gifted it, along with one million dollars, to the Methodist Church for use as a retreat and conference center, to be named Watson Homestead in memory of his parents. Watson Homestead became independent of he church in 1995, and continues as a conference and retreat center. The one-room school that Watson attended as a child is still on the grounds.

Watson worked with local leaders to create a college in the Binghamton area, where IBM was founded and had major plants. In 1946, IBM provided land and funding for Triple Cities College, an extension of Syracuse University. Later it became known as Harpur College, and eventually evolved into Binghamton University. Its school of engineering and applied science is named the Thomas J. Watson College of Engineering and Applied Science. The IBM plant in the neighboring city of Endicott has since downsized drastically, however.

There are documented versions of similar quotes by other people in the early history of the computer. In 1946 Sir Charles Darwin (grandson of the famous naturalist), head of Britain’s NPL (National Physical Laboratory), where research into computers was taking place, wrote:

After World War II, Watson began work to further the extent of IBM’s influence abroad and in 1949, he created the IBM World Trade Corporation in order to oversee IBM’s foreign business.

Led by John Patterson, NCR was then one of the leading selling organizations, and John J. Range, its Buffalo branch manager, became almost a father figure for Watson and was a model for his sales and management style. Certainly in later years, in a 1952 interview, he claimed he learned more from Range than anyone else. But at first, he was a poor salesman, until Range took him personally in hand. Then he became the most successful salesman in the East, earning $100 per week.

Watson was chairman of the Elmira College centennial committee in 1955 and donated Watson Hall, primarily a music and mathematics academic building.

On May 8, 1956 Watson retired and his oldest son, Thomas J. Watson Jr., assumed the position of CEO. He died on June 19, 1956 in Manhattan, New York City. He was interred in Sleepy Hollow Cemetery in Sleepy Hollow, New York.

The story already had been described as a myth in 1973; the Economist quoted a Mr. Maney as “revealing that Watson never made his oft-quoted prediction that there was ‘a world market for maybe five computers.'”

Later attributions may be found in The Experts Speak, a book written by Christopher Cerf and Victor S. Navasky in 1984, however Cerf and Navasky just quote from a book written by Morgan and Langford, Facts and Fallacies. Another early article source (May 15, 1985) is a column by Neil Morgan, a San Diego Evening Tribune writer who wrote: “Forrest Shumway, chairman of The Signal Cos., doesn’t make predictions. His role model is Tom Watson, then IBM chairman, who said in 1958: ‘I think there is a world market for about five computers.'” The earliest known citation on the Internet is from 1986 on Usenet in the signature of a poster from Convex Computer Corporation as “‘I think there is a world market for about five computers’ —Remark attributed to Thomas J. Watson (Chairman of the Board of International Business Machines), 1943”. All these early quotes are questioned by Eric Weiss, an editor of the Annals of the History of Computing in ACS letters in 1985.

In 1985 the story was discussed on Usenet (in net.misc), without Watson’s name being attached. The original discussion has not survived, but an explanation has; it attributes a very similar quote to the Cambridge mathematician Professor Douglas Hartree, around 1951:

He was posthumously inducted into the Junior Achievement U.S. Business Hall of Fame in 1990.