Curse of Galedon
The Curse of Galedon was a name given to a bio-engineered plague accidentally unleashed on Galedon V, during fighting between the Federated Suns and Draconis Combine in 3069. It would later spread to An Ting by way of refugees from Galedon V. Both worlds were considered dead after its passing.
The "Double Cobra"
In 2903 news spread across the Draconis Combine of a massive plague sweeping through the Albiero and Bjarred Prefectures. Though an existing vaccine was available to treat what was being called "Albiero Consumption", it required advanced medical facilities lacking in both prefectures, placing Coordinator Taragi Kurita in a difficult position with some advisers counseling that both prefectures be placed under brutally strict quarantine and to sacrifice their populations to stop its spread, while others appealed to Taragi to honor his oath as Coordinator to protect the lives of the people who aided his eventual victory over the Inner Sphere. Ultimately Taragi ordered as much assistance as possible into the two stricken prefectures, scientists and medical experts from systems near the affected prefectures joining together specifically to combat the plague. Using samples from the Albiero Prefecture gained through strict protocols, this special medical task force finally succeeded in developing an inexpensive and easily prepared vaccine in 2904, saving millions of lives and preventing a near-total collapse of the Combine economy. 
With the crisis brought under control by 2907, all the medical facilities were closed down, save two whose research shifted from vaccinations and public health into a related field - biowarfare. While such weapons had not being seen since the First Succession War, the Draconis Combine Mustered Soldiery High Command had long considered biowarfare in the event of an overwhelming assault by its neighbors. After several months of extensive testing, a weaponized version of the plague was created after merging it with XCON-73, an Age of War-era viral experiment developed by the Draconis Combine in 2413, a slow-acting but extremely durable pathogen that spread quickly through the air and reacted mainly to enzymes in the bloodstream of its victims. The resulting virus, called the "Double Cobra" for its two transmission vectors, was theoretically more lethal than any other chemical or biological weapon known to be developed even at the technological height of the Star League, capable of infecting an entire planet within weeks (depending on exogenous environmental factors). 
When the full range of the virus and its effects were disclosed to new Coordinator Shinjiro Kurita, he immediately ordered the samples sealed and locked down, only in the case of extreme emergency - such as the imminent downfall of the Draconis Combine - would such a weapon be unleashed. Convinced that of its two neighbors that the Federated Suns was the only enemy capable of pushing the Combine to the brink, the DCMS High Command placed the Double Cobra in a buried vault complex on Galedon V, chosen for its proximity to the Federated Suns border.
The Curse Unleashed
The weapon would be unintentionally released in the midst of the Jihad. During a particularly brutal battle between Armed Forces of the Federated Suns units from the Draconis March and the DCMS defenders in an area called the Outermark Hills, the vault was breached by the violence taking place above ground, releasing the extremely virulent bioweapon into the atmosphere of Galedon V. As the battle with the last remaining Davions on planet ended, a new and much more deadly fight had begun. DCMS troops soon came down ill, and within weeks the infection had spread over much of Galedon V. Authorities attempted to treat the contaminated population, bringing in shipments of electrolytic base to the stricken system, though nothing stopped the progress of the virus. The plague's source was not known to most, though the higher ranks within the Combine did know of the facility's existence and importance; outside intelligence agents speculated that the plague was possibly the work of Word of Blake.
As the situation worsened on the planet, the Clan Snow Raven's Storm Crow Naval Pursuit Star arrived in-system, commanded by Star Admiral Lydia Sukhanov, Galaxy Commander Arianne D'Amone and Loremaster Klaus Harper, seeking revenge for the perceived Combine attack on their Swift Wing Naval Assault Star at Ramora. Upon entering the system, military installations on the planet were subject to a short Orbital Bombardment, destroying them. Granting the civilians one week to depart the system, the few DropShips on the planet did so in haste, though they were far too few to save very many people. All of the vessels were claimed as isorla by the Snow Ravens, and taken onto the CSR Mountbatten, and the CSR Nestling. Initial reports were unclear as to which ships came into contact with the plague. Regardless of this, after the week was up, the fleet began a sustained Orbital Bombardment of every major city on the planet, leaving the world in flames.
After the Snow Ravens departed the system, it soon became known that the plague was sweeping through both vessels. As understanding of what had happened registered with the officers, Star Admiral Troy McKenna initiated a Trial of Annihilation against both vessels, to prevent the infection of the entire Clan. This was complicated by the fact that officers on both plague-stricken WarShips were unwilling to accept their fate, choosing to fight for their lives. Both ships were destroyed by their fellow Clansmen after a bitterly fought engagement, before the survivors limped back to their base in the Outworlds Alliance. Raven scientists later identified the strain as XCON-73 from historical Star League Defense Force records.
Spreading the Disease
The Draconis government officials quarantined the planet, to prevent the spread of the plague within their realm. But it was too late. Refugees from Galedon V had made landfall on nearby An Ting, where they were welcomed by the planet's citizenry, offering them shelter and aid. After a week on the planet, the plague began to sweep through their camp and beyond. The entire continent was quarantined in an attempt to stop its spread, but rumors of "The Curse of Galedon" had roused the populace into violent protests and widespread panic. As mayhem broke out, the An Ting government quickly hired mercenaries to attempt to stop the spread of panicked and infected civilians by force, but this was to no avail. By 3070, the Combine government quarantined An Ting, as they had already done at Galedon V. No measure stopped the plague from running its course on either world. A reported thermonuclear strike was launched on Galedon V in hopes of killing the virus in February of 3070, but this further incident was denied by the Combine government on New Samarkand. Neither world would survive the outbreak of the Curse of Galedon, and in the end, both were total losses for the Draconis Combine.
- Jihad Hot Spots: 3070, p. 48, "Victory, at Cost"
- The Wars of Reaving, p. 43, "Scourging the Plague"
- House Kurita (The Draconis Combine), p. 78, "The Third Succession War - Regrets - The New Century - Operation Freedom"
- Handbook: House Kurita, pp. 56-57, "History of the Nation - The Third Succession War - The New Century - The Deadly Double Cobra"
- The Wars of Reaving pp. 42-43, "Retribution"
- Jihad Final Reckoning, pp. 46-47, "Jihad in Review"
- Jihad Hot Spots: 3070, pp. 50-51 "Flight of the Raven"
- Blake Ascending, pp. 210-211, "The Raven's Flight"
- Jihad Hot Spots: 3070, p. 98, "Panic and Pain"