Work much with assemblers? That pretty much was the other choice in those days. Ever try to port an assembler program to another architecture?
He was pioneer. And, he didn't stop with FORTRAN. He was the primary inventor of the [link|http://en.wikipedia.org/wiki/Backus-Naur_form|Backus-Naur form] for expressing the syntax and semantics of computer languages. He first used it in defining [link|http://en.wikipedia.org/wiki/Algol_language|ALGOL].