- Gray Monday and Clarion Note redirect here.
Known alternately as Gray Monday, the Blackout that happened on or around 7 August 3132 saw unknown perpetrators disable some 80 percent of the Hyperpulse Generator network in simultaneous attacks and acts of sabotage not only in the Inner Sphere, but also in the Clan Occupation Zones and the periphery, effectively crashing the network and crippling interstellar communications. The Clans of the Inner Sphere were affected as well.
As a result of the Blackout, interstellar communication by and large collapsed, and was reduced to relaying messages via JumpShip in "pony express"-style. By early 3134, Paladin Kelson Sorenson and a select group of Republic of the Sphere knights and diplomats had united a disparate collection of cargo lines, free traders and repurposed military vessels into a relay network dubbed "Solar Express".
The communications blackout had widespread and far reaching ramifications, plunging the Inner Sphere into chaos. Civil unrest grew when it became apparent that the Blackout would not be quick or easy to fix.
There were in fact two simultaneous attack vectors against the HPG grid which are lumped together in the public perception of the Blackout.
Overall, 77 percent of all HPGs in the Inner Sphere succumbed to HPG Core burnout (later revealed to be a result of the "Clarion Note" protocol, see below) or other technological glitches, and another 3 percent were sabotaged or attacked outright. The HPGs that were directly attacked on 7 August were those that were somehow immune to Clarion Note. Although sources on the Blackout tend to lump the force-of-arms and sabotage attacks in with the Clarion Note core burnout, it is worth noting that the direct attacks apparently sought to disable the HPGs without destroying them, in a fashion where repairs were possible, whereas Clarion Note utterly destroyed the affected HPGs.
Most HPGs were actually taken down not by force of arms or on-site sabotage but in a more insidious way, by what appeared to be some sort of system-virus which caused the HPG core to overload and burn itself out with little collateral damage.
On Thursday, 4 August 3132, several class A HPG stations across the Inner Sphere began reporting strange and disruptive power spikes and signal modulations, though at the time these were regarded as isolated cases and it was expected that the problem would eventually correct itself. On Sunday, 7 August, affected HPGs began to fail one by one. Even brand-new replacement cores showed the same symptoms and burned out. This proved impossible to fix, and Tucker Harwell eventually surmised that the cause must lie with the medium of hyperspace itself.
Harwell later discovered references to a "Clarion Note" emergency protocol, which describes the use of a Super-HPG to disrupt interstellar communication in an unspecified way. Clarion Note was known to–and possibly devised by–the Word of Blake, who considered it a weapon of mass destruction and never actually used it. Context implies that Clarion Note would have affected hyperspace in such a way as to burn out HPG cores.
Evidence gathered by Harwell indicated that Devlin Stone's Republic of the Sphere had acquired the technology, and that the protocol had been initiated.
Also on 7 August, the same day that HPGs began to burn out due to Clarion Note, most if not all ComStar alpha circuit HPGs and many on the beta circuit were attacked and disabled. Most of the beta circuit stations were taken down over the next two weeks. It is not entirely clear from the wording if these "attacks" refer to force of arms and sabotage only, or include the core burnouts that began to materialize on the same day, as only a small fraction (3 out of 80 percent) of all HPGs were attacked directly.
The attack patterns included unspecified standoff weapons, missiles and other DropShip weapons, aerospace fighter strafing attacks, a zero-g assault team, a person in a guided VIP tour drawing a laser gun and destroying critical components before being shot by security, and one case of an undisclosed class A station being attacked by a squad of battlearmor troopers using an entirely unknown battlearmor design. The Vega HPG was one of the first to be attacked by force of arms.
Some stations were warned and defended themselves against the attack, and some could effect (crude) repairs. Still, 80 percent of the HPG grid was effectively taken down. Computer viruses were used to disrupt communication between arrays and ground stations. A few HPG stations remained technically functional but were incapacitated by different, sometimes bizarre failures such as being able to transmit but unable to receive data packages (Ayacucho station) or looping all outgoing transmissions right back to themselves (Jacson station).
Overall, the impression was that the attacks and acts of sabotage were surgical strikes that took out the HPGs without destroying them outright, and that the damage could be repaired; however, it vastly overtaxed Inner Sphere capacity for building replacement parts for devices that had been built to last centuries, especially with technology and industrial capacity having been degraded by the Succession Wars era.
It was specifically mentioned that 80 percent of the alpha circuit HPGs were damaged, with context suggesting that the "damage" referred to is more the repairable damage from direct attacks as opposed to total loss from HPG core burnout through Clarion Note.
Although the first signs of the Blackout appeared as early as 4 August, the direct attacks against HPG stations happened on 7 August, the same day the first HPGs experienced core burnouts. Thus, Sunday, 7 August 3132, is usually given as the date for the Blackout.
It has been speculated that the appellation "Gray Monday" for a date that is actually a Sunday comes from the fact that the full impact of the event was not felt until the following day (Monday, 8 August 3132).
Despite the considerable differences between Clan and ComStar HPG protocols and years spent by ComStar's programmers trawling through centuries of kludged-together code updates and patches nothing was found, and even newly manufactured cores showed the exact same symptoms before burning out themselves. ComStar, whose primary reason for existence was the operation and maintenance of the HPG network, threw everything at the problem, but save for restoring the HPG on Wyatt in 3135, and Millungera in 3137, temporarily in the latter case, nothing has worked, threatening the organization with irrelevancy, bankruptcy and total collapse. (The dying organization unwisely began to build up a military arm in secret, and was subsequently forcibly integrated into the Republic of the Sphere in 3145, terminating ComStar after 357 years of existence.)
Republic intelligence at one point stated that some HPG stations had effected "crude repairs" in the aftermath of the attacks, but from the context this apparently refers to secondary equipment that was damaged by sabotage or force of arms, and not to HPG cores.
The total extent of the Blackout is unknown, but it is evident that it affected all of the Inner Sphere and near periphery (with the periphery boundary largely defined by the extent of the HPG network). However, there are indications that Clarion Note did not reach into the Deep Periphery, as the Escorpion Imperio was not affected at all.
With the saboteurs either escaping or dying before interrogation, and no known casualties among the attacking military forces, their identity remains a mystery. The sole piece of identifying information was a strange insignia worn by some of the attackers: a snake coiled around a sword and set against a blood-red disk.
In 3151, after Terra had been conquered by Clan Wolf, Devlin Stone claimed on his deathbed that he had uncovered that the Blackout had been caused by Word of Blake deep-cover cell, who activated Stone's Clarion Note protocol to make the Inner Sphere tear itself apart; he did not offer any proof or evidence though.
Only a handful of HPG stations throughout the Inner Sphere survived. The HPG's ability to send messages to places up to 50 (A class HPGs) or 30 (B class stations) light years away considerably boosted the strategic importance of the worlds with functional HPGs (a working HPG is required to send messages, but not to receive them as HPGs effectively "jump" radio waves which can be received with regular radio equipment). Known worlds with working HPGs after the Blackout include:
- Achernar  (class unknown)
- Albalii (class unknown)
- Algot (class B)
- Ayacucho (class unknown) - send only; incapable of receiving "anything but the simplest carrier packet" which is noteworthy insofar as HPGs send regular radio signals through hyperspace that require no special technology to receive
- Altdorf (class unknown) 
- Bondurant (class unknown)
- Devil's Rock (class unknown)
- Gacrux  (class unknown)
- Genoa  (class unknown)
- Glenmora (class unknown) 
- Hsien  (class B)
- Imbros III (restored 3133) (class unknown)
- Irian  (class A)
- Jacson (class unknown) - technically functional but useless as hyperspace loop routes all messages right back to Jacson HPG
- Kessel  (class B)
- Menkar  (class unknown)
- Millungera (class unknown) - temporarily; HPG fix did not last
- New Aragon  (class A as of 3067, class B as of 3130)
- Northwind  (class B)
- Palmyra (class unknown) - HPG core destroyed or irreparably damaged during the Battle of Palmyra in 3144
- Ronel  (class unknown)
- Rowe (class unknown) 
- Shasta (class unknown)
- Terra  (class A)
- Thorin  (class A)
- Towne  (class unknown)
- Tsamma (class B) - unclear; ambiguously noted as an "AFFS hub"
- Wyatt (class unknown)
- In the BattleCorps PDF edition of the novel A Bonfire of Worlds, the date of Gray Monday is given as 1 August (instead of 7 August) which, being a Monday, may originally have been the correct date. However, according to the Line Developer, the date is corrected to 7 August in a proof of the novel which is in line with virtually all other Dark Age era publications (save one novel by Blaine Pardoe).
- Loss of HPGs in the periphery confirmed by Line Developer Herbert A. Beas II in an official chat on 24 February 2013; see also this article's Talk page
- Era Report: 3145, p. 12, "History and Review - The Fall of Darkness - What about the Clans?"
- Era Report: Dark Age, p. 5
- Era Digest: Dark Age, p. 4 "Gray Monday"
- Era Report: 3145, p. 12, "History and Review - The Fall of Darkness"
- A Bonfire of Worlds, Ch. 10
- In Ghost War, chapter 14, Janella Lakewood mentions "Hitting all of the alpha circuit in one fell swoop" while an earlier report just said that "stations on the alpha circuit" were hit.
- Ghost War, chapter 14
- A Call to Arms p. 143
- Ghost War, chapter 11
- By Line Developer Herbert A. Beas II; ; see also this article's Talk page
- Operational Turning Points Hanseatic Crusade, p. 10
- Hour of the Wolf, p. 365
- A Call to Arms
- Era Digest: Dark Age, p. 4 "Functional Republic HPGs as of 01 January 3135"
- By Temptations and by War
- Redemption Rift, Part 3, p. 11
- Fire at Will
- Redemption Rift, Part 1, p. 37
- Flight of the Falcon
- Fire at Will; restarted by ComStar during timeframe of novel, but A Bonfire of Worlds mentions that it didn't last
- Era Report: 3145, p. 34
- A Call to Arms, Fortress Republic
- Redemption Rift, Part 3, p. 11
- Target of Opportunity
- A Bonfire of Worlds indicates it is still operating in 3143.
- Catalyst Game Labs: "Correct date for Gray Monday - 01 or 07 Aug 3132?"