In the most significant trade in the history of the franchise, the Washington Capitals yesterday sent Ryan Walter, the team captain, and defenseman Rick Green to the Montreal Canadiens in exchange for defensive all-stars Rod Langway and Brian Engblom, center Doug Jarvis and forward Craig Laughlin.

"This trade makes the Capitals competitive," David Poile, Washington's new general manager, said at a news conference at Capital Centre. "We've added four quality players. For the first time in Capitals history, we have a defense."

Poile admitted that without Walter, a left wing who scored 38 goals last season, "we'll be missing some goals, but we have added defensive specialists, and the Caps can be a defensive club."

Walter, 24, was the second man selected in the 1978 draft. Green, 26, was the first player taken in the 1976 draft.

Langway, 25, and Engblom, 27, played as a defensive unit for Montreal most of last season. Engblom was the league's leading plus-minus defenseman (plus 78), and was voted to the NHL's second all-star team.

Langway, whom Poile called "the meaner and more aggressive of the two defensemen," was a first-team all-star for the Prince of Wales Conference.

Citing heavy Canadian taxes on his salary, Langway had said frequently he wanted to play hockey in the United States.

Jarvis, 27, has not missed a game during his seven years with Montreal. A defensive forward, he scored 20 goals and had 28 assists last year. Poile called Jarvis "a key to the faceoffs for us."

Laughlin, regarded as an enforcer, spent the early part of last season with Montreal's Nova Scotia farm club before joining the parent team.

"He's kind of a dark horse, because he only played half a year in the NHL," said Poile. "But he can play all three forward positions."

According to Poile, the deal had its beginnings early last week, on his second day as Washington's general manager.

"Irving Grundman (Montreal executive vice president) called to congratulate me on my new job, and we started talking shop," he said.

The Canadiens had made no secret of their desire to acquire Walter, who provides a sizable winger for Montreal.

Earlier this summer, Walter, whose contract with the Capitals was up for renegotiation, said he would be pleased to go to Montreal. "But I'd also be glad to stay in Washington," he said at the time.

Neither Walter nor Green could be reached yesterday.

"My approach in making this trade was that if we talked about Walter going to Montreal, then we would want a top defenseman back," Poile said.

After discussions with Grundman, Poile said he agreed to the deal subject to the approval of team owner Abe Pollin and Dick Patrick, the team's executive vice president.

Patrick attended yesterday's session. Pollin did not.

Asked about the former Canadiens' reactions to leaving hockey's capital to join the Capitals, Poile said he had not spoken with any of them yet, but felt "confident they'll welcome the opportunity to come to the Caps."

Langway, speaking on a Montreal radio show, said he was "ecstatic," and said Irving Grundman had made "the worst trade in the history of the NHL."

Poile talked with Walter and Green early yesterday. "I don't think it's set in to them yet. But it's a positive move for them; they have a chance to go to a team that's thinking of winning the Stanley Cup."

Poile stopped short of predicting champagne for the Capitals, but said, "I am committed to making the playoffs. I said before I thought we'd make the playoffs."

With Walter and Green gone, Coach Bryan Murray joked that, "The first thing I complained about to David was this idea of trading players, when I had some idea who would play together. But we'll find the right combinations."

Murray did not indicate who will replace Walter as captain. "I will discuss the captaincy with the people who'll be part of it and then will make the selection."

Poile said he realizes Walter might be missed as a leader, but "I don't see why Engblom and Langway can't lead."

"I was never dissatisfied with Walter," Murray said, "and Rick Green was the top defenseman on the team. From a personal view, this is tough."

Green, who had been unable to progress from competent to superior, said last fall that the Capitals' losing ways affected him.

"Losing night after night is frustrating," he said. "It's tough to get pumped up when you're trying and things aren't bouncing your way."

Poile acknowledged the contribution of the two players to Washington, saying he was "aware of what Ryan Walter and Rick Green have done to establish the Capitals, but I am here to strengthen the team. I'm confident this trade does just that."

Earlier this week, Poile traded goalie Mike Palmateer to Toronto for future considerations.

"Those future considerations are up in the air," he said, depending upon how well Palmateer's injured knee allows him to perform at the Maple Leafs camp.

Poile announced that "Pat Riggin is for sure our No. 1 goalie," then later retracted that statement, saying, "I have enough confidence in Dave Parro and Riggin to know we didn't need the uneasiness of three goalies in training camp."