The NHL as we know it was largely formed by the events of March 30, 1979.
The World Hockey Association, which began play in the 1972-73 season, sent salaries soaring for many players but led to numerous franchises being relocated or going under. The two sides finally made peace when the NHL voted to absorb four WHA teams 38 years ago.
The four WHA members chosen to join the NHL in a 14-3 vote were the Edmonton Oilers, New England Whalers, Quebec Nordiques and Winnipeg Jets. They were labeled expansion teams and paid $6 million each to enter the NHL; the 17 teams they were joining shared in the $24 million.
Video: Memories: NHL adds WHA clubs, expands to 21 teams
Two other WHA teams, the Birmingham Bulls and Cincinnati Stingers, were dissolved at the end of the WHA's 1978-79 season; their owners were compensated and their players put into a talent pool for the new 21-team NHL.
The deal was the culmination of years of discussion, some clandestine, that brought the two sides together. Not everyone was happy about it, but the prevailing opinion was that it would improve the quality of the sport.
"There will be a new rejuvenation in the NHL," League President John Ziegler said after the agreement was announced.
The WHA teams came into the NHL with their old names (although New England was rechristened as the Hartford Whalers) and none had to pay a territorial indemnity (as the New York Islanders did to the New York Rangers in 1972). But they didn't arrive whole: The newcomers were allowed to protect two skaters and two goaltenders, with the remaining players made available to the 17 existing NHL teams, who were also allowed to claim any WHA players whose rights they held.
The agreement included an expansion draft to stock the newcomers; each of the 17 existing teams were allowed to protect 15 skaters and two goaltenders. The 21 teams were aligned in four divisions for 1979-80, with 16 teams advancing to the Stanley Cup Playoffs. The newcomers were put at the bottom of the each round in the 1979 NHL Draft, although that didn't stop teams like the Nordiques (Michel Goulet) and Oilers (Kevin Lowe) from finding top-end talent at the bottom of the first round.
The expansion brought two hockey icons back to the NHL for a curtain call.
Gordie Howe, who had retired in 1971 after 25 seasons with the Detroit Red Wings but returned to the ice two years later to play with his sons in the WHA, was a member of the Whalers (as were sons Mark Howe and Marty Howe). Bobby Hull, a five-time 50-goal scorer with the Chicago Blackhawks before signing with the Jets in 1972, played 18 games for Winnipeg and nine for Hartford after being traded. Each retired after the 1979-80 season.
It also heralded the arrival of the next wave of stars.
Luckily for the Oilers, they were the only team in either league that had rights to a skinny 18-year-old center named Wayne Gretzky, who had signed with the WHA's Indianapolis Racers at age 17 and been traded to the Oilers early in the 1978-79 season. No NHL team owned his rights, and the Oilers were able to keep Gretzky, who became the cornerstone of their 1980s dynasty and set dozens of NHL scoring records that endure to this day.
Though the four teams essentially were treated as new entities, any thought that they'd be easy marks for the established teams disappeared quickly. Hartford and Edmonton each made the Stanley Cup Playoffs in its first NHL season, and the Oilers won their first division title in 1982 and raised the Stanley Cup two years later.
Perhaps the most relieved person after the expansion was announced was Ziegler, who had worked for most of the previous two years to put together a deal.
"It was as demanding as anything I've ever handled," he said after the announcement, "much tougher than any lawsuit I took as a lawyer, because in litigation you feel in control, and I never felt that control during expansion."