williams graduated from the royal military academy sandhurst in august 1957, entering into the royal artillery as a second lieutenant. he was promoted to the rank of lieutenant in august 1959, with promotion to captain coming in august 1963. he became a major in december 1968. in 1975, he gained the rank of lieutenant colonel, with promotion to colonel in june 1983. he gained his final promotion to brigadier in december 1987, with seniority to june 1987. he retired from military service in november 1991.