CSL was found responsible for the disastrous September 1949 fire and destruction of its ship the SS Noronic in Toronto Harbour. The fire swept through the ship killing 118 to 139 passengers (many as they slept), but no members of the crew. Inadequate alarm, passenger evacuation plans, and neglected extinguishing systems are found at fault. The captain was suspended one year for abandoning the ship before ensuring crew and passengers were safe.
In 1951, Sir James Dunn, the owner of Algoma Steel, gained effective control over the company. Following his passing in 1956, Dunn's estate would eventually sell off the CSL shares and in 1963 Paul Desmarais would acquire a major position until taking effective control a few years later.
CSL saw operations increase exponentially in the late 1950s with the opening of the expanded St. Lawrence Seaway and the timely discovery and exploitation of some of the world's largest iron ore deposits on the Labrador Peninsula in Labrador City, Schefferville, and Mont Wright. Ore was moved to Sept-Îles and Port Cartier by the Quebec, North Shore and Labrador Railway and Cartier Railway respectively, where it was then loaded into bulk carriers for transfer to Canadian and U.S. steel mills on the Great Lakes. CSL exploited this traffic by continually refining its self-unloading bulk carrier designs, coupled with improvements in stevedoring at various ports to arrive at a minimal number of human operators required.
At this time, CSL was given elevated status, where in the words of Power Corporation "...in order to increase its [Power Corporation's] own cash flow and take advantage of new federal tax regulations benefiting operating companies over holding companies, CSL took over most of Power’s investment portfolio at book value."
In 1976, Power Corporation reversed itself and took over the investment portfolio which had been sold to CSL five years earlier. CSL reverted to an operating division of Power Corporation at this time. On June 7, 1981, CSL President and CEO Paul Martin announced plans to expand outside of the Great Lakes and St. Lawrence River: "The Great Lakes are essentially a Canadian pond... Canadians have captured 95 percent of the business. Now we want our chance to try our wings on the oceans."
On August 9, 1983 citing federal government interference in the shipping industry, Martin stated: "then... they are going to come in with some grand and glorious package that will give the government control of the industry because they don't understand private enterprise."
By the mid-1980s, CSL's only remaining shipyard (Collingwood) was undergoing financial difficulties and was closed on September 12, 1986 with the loss of 800 jobs. At the same time, CSL Group Inc.'s expansion outside of Canada was well underway. In November, 1988 President and CEO Paul Martin was elected as a Member of Parliament and stepped aside from directing the day-to-day operations of the company.
In March 1991, following changes to Canada's taxation laws regarding international earnings, CSL backed away from threats to move its headquarters outside of Canada, however in December the president who replaced Martin resigned in opposition to plans to move international operations outside the country.
Replacement management in April, 1992 formed a new CSL Group Inc. subsidiary headquartered in Massachusetts to be called CSL International Inc. Canada Steamship Lines Inc. would remain as the Canadian operation under CSL Group Inc., and the conglomerate would remain headquartered in Montreal.
In November, 1993 the newly re-elected Paul Martin was appointed to the cabinet and named Minister of Finance. On February 1, 1994 Martin placed his shares in CSL Group Inc. under a "Supervisory Agreement" to be managed by lawyers and financial advisors, although he would be allowed to intervene in company decision-making should events warrant.
In June, 2002 Martin quit the cabinet as Minister of Finance to pursue a bid for leadership of the Liberal Party of Canada. On March 11, 2003 Martin bowed to public and media pressure on his interest in CSL Group Inc. and announced that he would sell his interests in the company to his three sons, saying that his ownership would "provide an unnecessary distraction during the leadership race."
On December 12, 2003 Martin becomes the 21st Prime Minister of Canada. On January 28, 2004 the federal government, in response to opposition party and media enquiries, revealed that CSL Group Inc. had received $162 million in federal government contracts, grants and loans since Paul Martin became Minister of Finance in 1993. Earlier figures released in 2003 had suggested CSL Group Inc. had only earned $137,000 in federal government contracts during this time period.
Atlantic Erie, Atlantic Huron, Atlantic Superior, CSL Assiniboine, CSL Laurentian, CSL Niagara, CSL Tadoussac, Frontenac, Halifax, Nanticoke, Rt. Hon. Paul J. Martin (named after Paul Martin Sr.), Birchglen, Cedarglen, Pineglen, Spruceglen