In 1956 the traditional Big '10' League was divided, its Western Division became the Western Ontario Junior "B" Hockey League, and the Central Division became the Central Junior "B" Hockey League.
In the 1960s, the Western Junior "B" Hockey League was arguably the top league of Junior "B" hockey in Ontario. The Western's brass and the team owners felt that they should, as a whole, be promoted to Junior "A" status. In 1968 they pushed the issue with the Ontario Hockey Association. The OHA refused the promotion and in return the league declared itself renegade. Declaring themselves the Western Junior "A" Hockey League, the WOJAHL operated independently for the next two seasons.
After the 1969 playoffs, the WOJAHL champion St. Thomas Barons, starring future NHLerKen Murray, faced off against future Hockey Hall of FamerBobby Clarke and the Flin Flon Bombers of the Western Canada Hockey League to determine a National Champion outside of the Canadian Amateur Hockey Association. The first two games of the Best-of-Seven series took place in St. Thomas, Ontario. Flin Flon won game one 6-2, while St. Thomas returned the favour in game two with a 6-3 win. The teams then shipped out to Flin Flon, where the Bombers took game three 5-0. In game four, the Bombers led 4-0 at 10:10 of the second period, and the last of two brawls in the game would break out. In retaliation, the Barons walked off the ice. When St. Thomas made it clear they would not finish the series, the Canadian Hockey Association awarded the championship to the Bombers. Coach Keith Kewly and Manager Jack Cassidy were suspended one season by their league and the team was fined $700. The town of St. Thomas had to raise $4500 to bring the team back home from Manitoba. Initially the CHA suspended the Barons for the entire 1969-70 season, but the suspension was overturned by the WOJAHL.
In 1970, the Top Tier of Junior Hockey in Ontario broke away from the OHA as well. To save face, the OHA opened negotiations with the WOJAHL. The league was welcomed back into the OHA as the top level in its system and changed its name to the Southern Ontario Junior "A" Hockey League.
The 1971 League title went to the Detroit Jr. Red Wings, starring Mark Howe and Marty Howe, sons of legend Gordie Howe. Detroit defeated Guelph 3-games-to-2 with two ties to clinch the title. Detroit went on to defeat the Ottawa M & W Rangers in the quarterfinals of the Centennial Cup before losing to the Charlottetown Islanders in the Eastern Final. The next season saw the Guelph CMC's challenge and defeat Detroit in the final 4-games-to-1. The CMC's pushed further and ended up winning the Manitoba Centennial Cup as Canadian Tier II Junior "A" Champions.
The '75 title was won by the CMC's again. They made it all the way to the National title, but fell to the Alberta Junior Hockey League champion. In 1975-76, the CMC's were bought and renamed the Guelph Platers. They won the league once again, and moved on to the national title playdowns. Their first opponent was the Rockland Nationals of the Central Junior A Hockey League. After going up 3-games-to-none on them, the Platers fell apart and lost in seven games.
In 1976-77 the Collingwood Blues also joined the league but three other teams dropped out, reducing the number of clubs to four. The Niagara Falls Flyers folded to make way for a new OHL franchise in that city, the Welland Sabres also folded and Chatham returned to Junior B.