Prior to that, he worked for NCR in charge of its sales force, until he was convicted for illegal anti-competitive sales practices (e.g. he used to have people sell deliberately faulty cash registers, either second-hand NCR or from competitors; soon after the second-hand NCR or competitors cash register failed, an NCR salesperson would arrive to sell them a brand new NCR cash register). He was sentenced, along with John H. Patterson (the owner of NCR), to one year of imprisonment. Their conviction was unpopular with the public, due to the efforts of Patterson and Watson to help those affected by the 1913 Dayton, Ohio floods, but efforts to have them pardoned by President Wilson were unsuccessful. However, the Court of Appeals overturned the conviction on appeal in 1915, on the grounds that important defense evidence should have been admitted.
He was famous for making his salespeople at both NCR and IBM attend sing-a-longs (see The IBM Songbook below).
In 1937, Watson received the Eagle with Star medal from Adolf Hitler, for the help IBM subsidiary Dehomag and its Hollerith punchcard machines provided the Nazi regime for tabulating census data. After the outbreak of the World War Two, Watson returned the medal, yet ensured the survival of Dehomag. See Edwin Black's 'IBM and the Holocaust.'
He is known for his 1943 statement: "I think there is a world market for maybe five computers".