The Washington Capitals appropriately chose Pearl Harbor Day for their latest disaster. Not only did the Capitals play poorly in a 7-3 setback by the Boston Bruins, but they also lost another defenseman as Pat Ribble jammed his right thumb early in the second period.

"I hope it's just hyperextended or something, but the doc thinks it might be ligaments," Ribble said. "I dislocated the thumb last year and was out three weeks and I hope this isn't the same. Then it was out of joint, though, and it's not out of joint this time."

The loss of Ribble and the extended absence of Alan Hangsleben, whose nose was badly cut in a fight with Stan Jonathan, contributed to the size of the score. The Capitals, already missing defensemen Rick Green, Yvon Labre, Paul MacKinnon and Rick Smith with injuries, were forced to depend on Pierre Bouchard and three rookie defenders: Darren Veitch, Howard Walker and Jim McTaggart, who was playing his first NHL game.

"We were under a lot of pressure in our end zone and with the inexperienced defense we had a lot of problems," said Coach Gary Green. "But it wasn't just the defense. The forwards didn't back them up and there was no concerted effort on offense. We miss Bengt Gustafsson (who dislocated a shoulder Saturday), too. No question, he adds to both our offensive and defensive game."

The Bruins were not overpowering in snapping the Capitals' seven-game unbeaten streak. Boston benefited from the Captials' loose play and was actually outshot, 30-28.

In the first period, the Bruins managed only three shots, but they scored on the first two. Peter McNab, son of the Capital general manager, converted a power-play setup by Jean Ratelle at 4:49 and Terry O'Reilly connected on a superb effort at 13:52.

O'Reilly was tripped by Veitch and slid in front of the goal. While sitting on the ice, he managed to bat the puck past goalie Wayne Stephenson, who was not sharp tonight, either.

Wayne Cashman, left unguarded in front, used Steve Kasper's pass to make it 3-0 on Boston's first shot of the second period. A minute later, Dwight Foster cut around McTaggart and fired the puck off Stephenson's pad. Washington's Paul Mulvey tried to push it out of the crease, but Jonathan pushed it in for a 4-0 lead. With Ribble hurt, it was just a matter thereafter of deciding the final score and entertaining the 9,043 fans with some fistic accoutrements.

McNab collected his second goal, while Kasper and Dick Redmond also hit for the Bruins, who were making Coach Gerry Cheevers' 40th birthday a happy one. On the Washington side, Mulvey recorded a goal for the third straight game; Bob Kelly netted his eighth in the last seven games, and Dennis Maruk boosted his season total to 22. Ryan Walter assisted on Mulvey's goal to run his club record of assists in consecutive games to seven. m

The main event on the fight card, which brought the fans leaping to their feet in obvious joy, featured Hangsleben and Jonathan, with each landing some solid punches. But an early left by Jonathan, with the thumb apparently the chief weapon, gouged a chunk out of Hangsleben's nose and sent him off for repairs.

"He was clutching and grabbing all the way down," Hangsleben said. "It was going on quite a while. It's just part of the game that shouldn't be there. It's supposed to be a finesse game, not Saturday afternoon crucifying the Christians in the Colosseum."

The fans reacted favorably to the gladiatorial combat. There was more that followed, as Walker hit O'Reilly with his stick and little-used Al Secord felt it necessary to go after Walker. As an added attraction, Kelly divided two falls and exchanged a lot of punches with Boston rookie Larry Melnyk.

Washington never has won in 15 visits to Boston Garden. Before the game, memories of the Capitals' first visit here, a 10-4 defeat, were exchanged with the former general manager, Milt Schmidt, now a host in a Garden club, and the first Washington coach, Jimmy Anderson, here in his capacity as a scout for Vancouver.

"That team just didn't pull together," Anderson recalled. "Everybody was just concerned about himself."

Today's Capitals pride themselves on togetherness and they have succeeded admirably in building a 9-7-10 record. For one night, however, they were living in the past.