Down they trucked from the hills of Hanover, mean and undefeated. They came in hordes, green hordes, ready to triumph by day and party by night. They had taken care of Yale the week before, and after they took care of Harvard, the Ivy title would be theirs for, well, the taking.

Yes, the Dartmouths were ready on Saturday, but then the tailgating ended and they began to play football. Three hours later they didn't look so mean.

Nor were they still undefeated, for in a performance that will be hard to duplicate, the Crimson took to the Stadium turf and basically beat the hell out of Dartmouth to the misleading tune of 31-25. The Big Green was outhit, outplayed, outfinessed and at times, just plain out of it.

They were out of it early, when Harvard built a 21-7 lead before most of the tailgaters had digested their lunches, and they were out of it late, when a varied assortment of Crimson defenders plugged the leaks just when it appeared the dam might break.

And when it was over, and the rain had stopped and the sun had made its first Saturday appearance in Cambridge in many a moon, it was the Crimson that stood alone atop the Ivy standings, 3-0 in the league, and doesn't the Colgate game seem semesters away?

Unlike Harvard's previous triumphs this year over Columbia and Cornell, this one had class. It was a solid, take-it-to-'em affair, the Crimson's finest hour since New Haven two years ago. Dartmouth just wasn't prepared for it.

Neither, for that matter, was the crowd, which had seen Harvard drop five in a row at home and which seemed a bit confused, in the best it's-too-good-to-be-true, so-it-can't-be-happening mold, when the Crimson jumped off to three quick touch-downs. Reality, at first, was too good to be real.

So was Harvard after the Big Green parlayed a sloppy Crimson hand-off into a fumble recovery and its only lead, 7-0, early in the first quarter. When the Dartmouths next looked up, they were trailing, 21-7, and wondering what had gone wrong.

First Larry Brown drove the Crimson 65 yards in nine plays, with Jon Sigillito doing the honors on an eight-yard pitchout. This march was the first of three in the opening half, when Harvard's offensive line treated the Dartmouths with Rodney Dangerfield-like respect. In other words, with none. The holes that opened were immense, and at least on this day, Brown, Sigillito, Ralph Polillio, and Chris Doherty looked like the Four Horsemen of Fresh Pond Parkway.

On his next possession, Brown showed that he's matured more as a quarterback in three weeks than most people do in four years. After a 22-yard leaping catch by Polillio and a 38-yard dash down the right sideline by Wayne (why isn't he used more?) Moore, Brown gave the Crimson its initial advantage on an eight-yard rollout.

Three weeks ago, if he hadn't been able to find an open receiver, Brown would have panicked. This week he coolly checked out the situation, tucked the pigskin under his arm and snuck into the right corner of the endzone.

If Dartmouth was worried now, it turned green (as in sick, not Big) when, early in the second frame, Sigillito did a little one step, two step for a seven-yard, his second, Harvard's third score. The Crimson was doing what it pleased, and it was pleased by what it was doing.

The visitors' Nick Lowery hit a 33-yard field goal, a chip shot for him, in the half's final minute to make the score 21-10 at intermission, and then, five minutes into quarter number three, it happened.

Back to pass, Brown couldn't find any red jerseys in the clear. Since the offensive line gave him half an hour to throw, Brown just stayed in the pocket, like a pitcher staring in to get a signal that he keeps shaking off, when he spotted Larry Hobdy breaking free over the middle.

Brown fired. The ball soared by Sigillito, who was also hanging out in the middle, and met Hobdy in mid-stride. The swift senior, a starter a year ago, Jim Curry's back-up this go-around, then made the most of his opportunity and outsprinted the world into the Dartmouth endzone.

Harvard led, 28-10, and Crimson fans reacted as though all final exams had been cancelled. Hobdy and Curry, meanwhile, graphically defined the meaning of embrace.

The Big Green refused to pack up and go look at the foliage, though. Steve Ferraris hit sneaky Jimmie Solomon on a 61-yard quick strike over the middle, and after Gary Bosnic drilled a 40-yard field goal for the home team, Buddy Teevens found Jeff Nadherny eight yards away and open in the endzone. And now it was 31-25 with two and a half minutes remaining.

Dartmouth got the ball back, but Harvard walked tall and said no to any Big Green miracles. Earlier in the final quarter a Paul Halas interception had stopped another Dartmouth drive; on this day the Big Green was meant to be stopped.

Halas's theft was the Crimson's third. Steve Potysman, who played a great game at cornerback, accounted for one in the third quarter, and Bob Baggott's weekly turnover, a Lou Piniella grab in the second that set up the Crimson's third score, represented the other.

And so on this morning of the 17th day in the Year of the Lord 1977, it is Harvard that stands as the leader of the pack. The season, of course, is hardly over, and yes, anything can happen in a month. But that's obvious, because a month ago, who would have predicted the Crimson to be soloing at the top this morning?