What happened there? Was it similar to the Breen Attack on Earth or did they conquer it for some time? Why was it never mentioned during later times?
Pretty sure they've clarified the attack isn't on Vulcan - it's on a Vulcan/Federation outpost somewhere closer to border.
The thing is, Earth (past the founding of the Federation) has only ever been bounced by 1) an entity 82 AUs wide capable of simply turning off orbital defenses, 2) an oddly singing device capable of turning off all defenses, 3) the Borg, and 4) a suicidal fleet of Breen, AFAWK anyway. Unless there are hidden depths to Klingon technology in DSC, I'd think 1 through 3 are out. And since when have Klingons been suicidal? Drunken talk basically never has led to a definitive end result. Timo Saloniemi
Space is big, unless Starfleet are a truly enormous operation there are limits to their ability to respond to threats caused by sheer physical factors like ship numbers and maximum speeds. Even if we imagine a perfect sensor grid, the Klingons could still do significant damage before they were stopped.
The question then becomes, why didn't they? And this attack on Vulcan may be the answer, the definition of the very best they could hope to achieve. Timo Saloniemi
We've only really seen Vulcan's response to incoming hostilities twice: TSFS: a rogue Klingon bird of Prey is able to safely land with a bunch of Starfleet fugitives on board. They were likely granted amnesty by Sarek and the Vulcan High Command, however. ST'09: Vulcan has basically the same defenses as Earth (i.e. none).
I was limiting the decision to the Prime universe. Should also consider the 22d , 23d or 24th centuries.
Did they? "The Vulcan defense vessels" were responding long before the envoy convoy was near the planet. In the 2009 movie, we supposedly saw an exceptional situation in two specific ways, on Earth and presumably on Vulcan: most starships were called away on that lark at Laurentius, and Nero supposedly had tortured some important codes out of key people he had captured. What Nero did with those codes exactly, we don't know. He wasn't a soldier, and he wasn't a master criminal who'd know to vary his modus operandi, but he did come from the future - perhaps he simply released some 24th century malware from his asocial media files or ventilation control computer which then utterly burned the 23rd century defense networks? DS9 gives us a good indication of why starships orbiting planets aren't a good idea for defending those planets. Fixed fortifications can defeat a thousand ships; defending ships would just get in the way. But all the threats at Earth either involve a superfoe turning off the fixed defenses, or omit the key scenes where the superfoe deals with them. On the other hand, Federation "outposts" never have defenses capable of warding off a starship. They are designated damsels in distress akin to "science ships" or "colonies". And in all eras, the cavalry arrives too late, supposedly because of a shortage of horses; I don't see why a 2220s Starfleet should have more ships per easy victim than the 2260s or 2370s Starfleet has. Timo Saloniemi