Beyond learning the general history of Edgar F.Codd, I found really interesting for one Codd's choice to move from England to the United States as he believed that it offered more opportunity however when he got here It took him 6 months to get a job. Something really important I read about was the importance of the relational model which completely changed the way datasets were looked at and the way they were studied and respected.
Another important development that I read about that I found interesting was the making of INGRES which initially was being made in order to produce a geographically-oriented system with graphical capabilitie, but after some time developed into the creation of a new commercial market of relational database systems that to this day are widely used from in government offices to even Cornell College