Port Adelaide's first preference to replace
Jack McCarthy as head coach was South Adelaide's
Jim Deane, but South Adelaide refused to release him from his contract. In his first year at Port, he won the club's best and fairest award and led the team to a preliminary final, where they were however well beaten by Glenelg. In 1951, he won his second SANFL premiership as a player and the first of a then record nine as a coach when he led Port Adelaide to an eleven-point win over
North Adelaide in the Grand Final after losing only one game on a Thebarton Oval mudheap all season. Under the coaching of Williams from 1950 until 1958, Port returned to a position of power in the league and along with the 1951 win they won five consecutive from 1954 to 1958 and finished second to West Torrens in 1953. After 1950, Port Adelaide only missed the Grand Final under Fos Williams guidance when they lost the preliminary to Norwood by eleven points in 1952. In 1953, Williams returned Port Adelaide to the Grand Final, a stage where the club would remain for seven consecutive seasons. During the 1953 SANFL Grand Final Port Adelaide would fall to West Torrens by 7 points. In 1954 Williams led Port Adelaide to its second premiership under his guidance, defeating his old club West Adelaide by 3 points in the
1954 SANFL Grand Final. In 1955, Port Adelaide defeated Norwood in the
1955 SANFL Grand Final by 63 points. In 1956, Williams again defeated his old club West Adelaide, this time by 16 points in the
1956 SANFL Grand Final. In
1957, Port Adelaide defeated Norwood for the second time in three years for the premiership. For the third time in five years, and what would be his last before retiring as a player and stepping away from football for 1959, Williams guided Port Adelaide to the
1958 SANFL premiership with a two point Grand Final victory over West Adelaide. After leaving
Alberton at the end of 1958, Williams' influence at Port Adelaide was still evident in his three-year absence with the team's style of play changing little under new coach (and Williams' old teammate)
Geof Motley. Motley took over as captain-coach and Port would win a
sixth successive flag in 1959 and finish third in 1960 and 1961 before Williams returned in 1962. During his time as captain-coach of Port Adelaide, Fos Williams wrote the club creed. == Year away from Football (1959) ==