One of my favourite computer history books is Stan Augarten's "Bit by Bit", which has an author-approved scanned copy at http://ds-wordpress.haverford.edu/bitbybit/
In it, the author makes the following assertion:
As a former military pilot, Tom Watson was quite familiar with radar and other avionic devices – the typical B-29 had about a thousand tubes – and he had a fine appreciation for the potential of electronic technology. Although Watson Senior and other old hands at the company believed that IBM’s customers would shy away from anything electronic, considering it too advanced and possibly unreliable, Watson decided to let his son test his hunch. ... To everyone’s surprise – including Tom’s – the entire lot was snapped up.
Allowing that bombsights and fire-control computers were still basically mechanical devices in 1946, should one assume that Watson Jr.'s enthusiasm was solely because he recognised that tubes (valves in UK English) could be reliable (and somebody in IBM had introduced him to the idea of digital electronics), or because the B-29 bomber contained digital equipment which has not so far been widely discussed?