It was the kind of day that made almost everyone happy.

Nearly everything came up perfect for the 85th Army-Navy game, which was welcomed back to Philadelphia after last year's game at the Rose Bowl in Pasadena. Unlike some recent Army-Navy games, which were played in bitter cold and rain and even darkness, conditions for this one were crisp and sunny, and the sellout crowd of 73,180 at Veterans Stadium was the first for an Army-Navy game in years.

The big bowl was a sea of yellow and gold -- buttons and berets. The brigade of midshipmen waved yellow "Go Navy" flags and made noise with clacking "applause jaws." Standing in the midst of this pregame racket, one could barely hear the cannons that were fired relentlessly from both sides of the field to get everybody in the proper mood.

Not that the entire brigade and the Army corps of cadets weren't ready.

"Last year we didn't have much of a chance," said Army's Kim Randall, a sophomore from Plymouth, Mass. "That was a really good time, but I think this could be even more fun -- if we win."

Two Army plebes agreed.

"The plebes will be able to fall out if we win," said Michelle Matthes of Wilmington, Del. "We get to talk in the mess hall. There are just less restrictions, athough that's just until Christmas. The whole corps will be happier, so the plebes will be happier."

"We're going to win," added Robin Lesjack of Milwaukee. The week at West Point had been "wild," according to Matthes. "Great," added Lesjack. "We had a big bonfire."

Similarly, the Navy contingent was ready, or so it seemed.

As the midshipmen sang out, "Go, Navy," Sandra Kirby of Beaumont, Tex., expressed little doubt that the midshipmen would continue their domination of Army. "They're not a little better," she suggested. "We're a lot better. We're the only team in the country to beat South Carolina."

Kirby said high jinks abounded in Annapolis this week, too. "Did you hear about the bleachers in the swimming pool? Somebody put the bleachers in the swimming pool."

"They've been keeping the plebes up pretty late all week," said one of them, Troye Crickette of Savannah, Ga. "They knock open the door and flick on the lights."

Before game time today, traffic snaked toward the stadium. Many of the cars, bedecked with Army or Navy banners and stickers, let one another change lanes with cheery waves instead of customary growls. If not every mustard dispenser worked, folks happily used catsup.

"Forty-two years ago today, I reported to the Army at Fort Dix," said one fan. "It was snowing like crazy. Today's a lot better."

Both sides marshaled their forces. Navy brought up two goats to the sideline: Billy XXII, who made his debut in 1979 and looked as though he might be getting old, and Billy XXIV, who looked like the new kid on the block. (Billy XXIII reportedly was too surly to make the traveling team.) But the Army countered with three mules. An omen?

The only thing that could quiet the pregame hoopla was a message from President Reagan piped into the stadium. He called the game "a great American tradition" and "a football game for all Americans."

These remarks were applauded by both sides and the game got underway once a whole host of cadets had been cleared from the field. They had run across to the Navy sideline and "attacked" a Navy float, a little battleship on wheels.

The sun continued to shine on the cadet side of the field all day, as Navy's was cast literally and figuratively into the shade. By the third period most of the cadets removed their jackets, revealing black "Goat Busters" jerseys. And by the fourth period, most of those cadets were shirtless, waving the jerseys in the air to the utter dismay of the midshipmen. Apparently feeling confident, some cadets unfurled a banner over the front building of one of their sections with a portrait of Reagan on a field of red and white stripes. It read: "You're working for one tough SOB."

With eight minutes to play, Navy managed its only touchdown, and the players didn't seem to mind a bit that the blue smoke from their booming cannon engulfed them on the sidelines.

But this was Army's day, its first victory over Navy since 1977. With 1:06 remaining in the game, Nate Sassaman, Army's gritty quarterback who was playing with three cracked ribs, but nevertheless was named player of the game, accepted hugs from his teammates on the field and trotted happily to the sideline to begin a celebration that would no doubt last long into the evening.

At the very end, the cadets charged on the field and raised the players to their shoulders while others began tearing down one set of goal posts. The jubilation was interrupted as West Point's alma mater was sung. The stadium fell silent, cadets and midshipmen stood at attention, blue haze from all the cannon shots hung in the air, and the goal post leaned precariously.

One Army player watched the scene on crutches. A fullback, Dave Pratt, had twisted his knee in practice Monday and had been knocked out of the game. "I cried," he said, but now he was doing just fine. "Feeling great," he said, as he hobbled up the tunnel to the Army dressing room. "Top of the world."

Pratt's teammates roared up the tunnel behind him. "That baby's ours," cried linebacker Marty Baptiste, meaning the Commander-in-Chief's Trophy that this year belongs to Army.