In three throne-like, red-velvet armchairs, the junta sat ramrod straight, eyes fixed directly on the altar ahead, oblivious, it seemed, to the glare of television lights and the dulcet strains of the choir of blind singers in sunglasses.

Behind the three commanders in chief, each in his Army, Navy or Air Force regalia, rows of men in uniform stretched out under the stained-glass windows and the high ceiling of the chapel.

Today was Navy Day, the traditional commemoration of the last century's battle against the Spanish. But today with the possibility of all-out war looming closer, this country is in no mood to celebrate.

At this solemn mass for the Argentine soldiers who have died in the Falklands conflict, President Leopoldo Galtieri suddenly choked up, and his eyes reddened.

"Confronted with the deaths of our soldiers, our tears well up," the bishop said in his sermon. As Galtieri walked out of the chapel, he embraced Cardinal Juan Carlos Aramburu, and, for a moment he cried silently, the tears visible in the gray light of a rainy morning.

Gen. Galtieri, a square-shouldered, silver-haired figure of Italian lineage who bears a resemblance to George C. Scott, is under extraordinary pressure. He is known to be a man of strong emotions. He has had trouble sleeping, he told a Mexican television reporter yesterday.

Around the capital, people say that Galtieri's days are numbered, that the surge of popular support for the invasion that rescued his shaky government will wear thin.

The talk may be nothing but rumors. But if the military suffers a decisive defeat by the British, or if it gives in on the issue of sovereignty, the junta could well fall, but no one knows who would inherit the power.

Earlier this morning, the man who sat next to Galtieri in the chapel, Adm. Jorge Anaya, commander in chief of the Navy, gave a short speech to Navy brass and a group of reporters gathered at the Admiralty headquarters.

"We have the conviction that we are only complying with our duty," said Anaya, a short, austere man with a sharp nose, small eyes and a reputation as the hard-liner and as the intelligence behind the invasion. "We are fighting with the fresh memory of our dead, which tightens our hearts and renews our efforts to vanquish in this just cause."

"These are difficult hours," Anaya added, reading from a prepared text. "The pain can break the spirit of the weak; therefore, we have to restrain our emotions and reaffirm the values of our struggle. Embracing these principles, irrigated with our blood, we stand up, proclaiming our truth, and we march to victory so that our sons will live, because to live without God, without honor and without glory, is to die without a fatherland."

In the speech, there was no mention of negotiations. The word peace never figured, a reflection of the general pessimism that seems to have enveloped the capital. It is the Navy that has lost the most men in the fighting and, by most accounts, it is the Navy that has most fiercely opposed any concessions during the negotiations.

"You may think I am a tool of the British . . . ," Secretary of State Alexander M. Haig Jr. reportedly said to the junta at one point. Steely-eyed, Anaya is reported to have replied, "That is exactly what we think."

Air Force Cmdr. Basilio Arturo Lami Dozo, the man in the third armchair, is not thought to be much more predisposed to compromise. Lami Dozo, a tall, square man with a stiff demeanor, is the least known of the three. It is said that he upholds the Air Force's tradition of keen competition with the Navy and the Army.

After the mass, as Galtieri walked red-eyed across the sidewalk, a reporter asked him if there was any chance for peace.

"Always," he replied.

A few minutes later, as Anaya walked out of the chapel, a reporter asked him what hopes he had for the negotiations. Without answering, he looked straight ahead, grim-faced, and climbed into a black limousine.