How long did the dark forest deterrence last?
Fifty-four years. That is the length of the Deterrence Era in Death's End, and it stands as the most stable stretch of peace in the entire timeline of the trilogy. What makes the number striking is how it was held up: not by fleets or treaties, but by one man sitting alone in an underground bunker with a single button at his hand.
The peace began when Luo Ji established the dark forest deterrence by turning the sun into a trigger for a gravitational-wave broadcast. From that moment, the two civilizations were bound to the same fate: destroy Earth, and Trisolaris dies with it.
Why did one person hold up fifty-four years of peace?
Because deterrence only works if the other side believes you will actually pull the trigger. Luo Ji served as the sole Swordholder for the entire era, and Trisolaris watched him through the sophons for all fifty-four years for one reason — to measure whether he would really press the button.
His answer never wavered. His resolve was cold and absolute, and no one doubted he would broadcast the coordinates if Earth were attacked. That certainty was the deterrence. The "deterrence probability" — the odds Trisolaris assigned to a human actually pressing the button — stayed high the whole time Luo Ji held the hilt. So the button was never pressed, yet its mere existence was the entire reason for the peace.
Why did it collapse in minutes?
The fatal weakness of the dark forest deterrence was that it hinged entirely on the credibility of a single person. The moment Cheng Xin took over as Swordholder, Trisolaris moved almost instantly, because the sophons had already told them what she was: a person driven by love and responsibility, someone who could not press a button that would doom two civilizations.
They were right. Trisolaran probes destroyed Earth's gravitational-wave transmitters within minutes, and Cheng Xin failed to press the button at the decisive moment. Fifty-four years of peace ended in the space of a few minutes. That contrast — half a century of stability undone by a few minutes of hesitation — is exactly why the Swordholder transfer is the turning point of the whole novel.
Did the collapse immediately expose Trisolaris?
No, and this is where people get confused. When deterrence fell, Earth's transmitters were already destroyed, so the coordinates were not broadcast from Earth. The signal that actually exposed both star systems came from a fugitive ship far out in space — a separate thread of the story. But for the plain question of how long the deterrence held, the answer is clean: fifty-four years of peace, one button, one man, and then minutes of collapse.