The true answer. Number one: Reach was the location of a Forerunner crystal, the power of which has the ability to give whoever touches it near "superpowers". The humans were unaware of this at the time, but they used Reach as a major smelting planet, exporting most of the fleet's titanium from the planet's mantle. Number two: Humans have the ability to operate Forerunner artifacts, say the crystal, more easily than the Covenant can. This threat must be exterminated so that the humans cannot have these superpowers. Number three: They are jealous of our apposable thumbs.

They did it to kill the humans, some of the humans had traces of forerunner DNA and the thought of the forerunners decendants being alive would completely undermine their religion. So the prophets ordered Reach glassed. The short form is: Politics.

Because the Covenant are mean.

[quote][b]Posted by:[/b] DorkLord54 It's because, while they were sitting on their chairs playing [i]WoW[/i], the Prophets got mad of being beaten by Chuck Norris and then having their chairs implode, thus causing them to not only buy new chairs, but as well get plastic surgery, thus why they look different then they did from [i]Halo Wars[/i] to [i]Halo 2[/i]. So, they hacked Chuck Norris' account and discovered he was on Reach to show the UNSC that the SPARTANs were not humanity's greatest fighting force. So, to rid themselves of the Chuck Norris threat, they sent a massive fleet to Reach, saying there was a crystal there, unaware that Norris was really the primary goal. And so, they glassed Reach. Unfortunately, Norris used his superpowers to escape Reach and ported three weeks into the future on Earth in exactly .001 seconds.[/quote] F.ucking winsauce!

They got bored.

Why did they glass any planets? I personally think Teddy bears filled with rocks is better.

Ummm you should read the books then. The Prophets learn that humans are desendants of the Forunners so they must not all have died. Meaning their entire religion is false so instead of facing a huge revolt they make up the excuse that Humans have been destroying Forunner artifacts and we are filth and we must all be destroyed.

Because they felt like doing so

[quote][b]Posted by:[/b] DorkLord54 It's because, while they were sitting on their chairs playing [i]WoW[/i], the Prophets got mad of being beaten by Chuck Norris and then having their chairs implode, thus causing them to not only buy new chairs, but as well get plastic surgery, thus why they look different then they did from [i]Halo Wars[/i] to [i]Halo 2[/i]. So, they hacked Chuck Norris' account and discovered he was on Reach to show the UNSC that the SPARTANs were not humanity's greatest fighting force. So, to rid themselves of the Chuck Norris threat, they sent a massive fleet to Reach, saying there was a crystal there, unaware that Norris was really the primary goal. And so, they glassed Reach. Unfortunately, Norris used his superpowers to escape Reach and ported three weeks into the future on Earth in exactly .001 seconds.[/quote] This this is the exact reason.

My guess they got wise enough to blow up the planet instead of sitting there waiting to be taken over by the humans again. Example:Harvest (I KNOW THAT GLASSED IS NOT THE SAME AS BLOWN UP)

[quote][b]Posted by:[/b] Rocko 1131 I didn't read the books, but in there does it say exactly why Reach was glassed? Are the covenant just genocidal? I don't believe that. They are obviously a race of high intelligence and would need a solid reason to destroy an inhabitable planet. What if the covenant found the Flood on Reach? What if they were trying to contain infection and destroy the parasite? That would be an excellent reason to glass Reach. Reach is a big planet, and it would be difficult to check every single nook and cranny. The flood were probably there the whole time and the humans just never found them, but the covenant did and set out to exterminate the parasite. Then war ensues because the humans don't like their home being destroyed, when in fact the covenant's motives were to destroy the Flood. Plausible idea? or do the books say something otherwise?[/quote] *spoilers* Reach is near the very end of the war. They glassed it and are genocidal to humans because the Prophets told them that they were heretics and vermin who would destroy Forerunner relics. The Forerunner are their gods, so that was about as bad as taking a crap in their Cheerios. The fact is though, Humans are the inheritors of the Forerunner, and that would DESTROY their religion. */spoilers*

The Covenant are a gathering a races that revere the forerunner as gods. They search for forerunner relics in search of knowledge and power. They have a sacred promise of the Halos which will take them on a great journey and make the gods alongside the forerunner. Truth translated some forerunner text as reclamation and the covenant believed that the covenant were their heirs. However a forerunner AI told truth that it was reclaimer and referred to humanity. This revelation told Truth that the great journey was a lie. And the covenant would be destroyed if people knew the truth. So he kept it secret and decided to tell the covenant that the humans were an affront to their gods and must be destroyed. And they led a genocidal campaign against them. They began destroying all of the human worlds. Reach was one of them. Its a pretty important planet as it was one of the last defenses of earth and the biggest most advanced military world.

[quote][b]Posted by:[/b] S_034 [quote][b]Posted by:[/b] fudgehog1925 [quote][b]Posted by:[/b] Herosmurff Do the covenant even know about the flood before Halo:ce?[/quote] No one did but the Forerunners.[/quote] Not true. It's been hinted at that the Covenant had at least a general-albiet flawed-understanding of the Flood prior to the opening of the Human-Covenant war. Most of their information, as far as we know, was based off of Forerunner inscriptions which they never fully comprehended. Basically, they knew that the Flood existed and that it was incredibly dangerous, but little more, and we've been given almost no evidence to suggest that the Covenant had met the Flood face-to-face prior to the events of Halo Wars. However, it is a FACT that the Covenant encountered the Flood during the events in that game. Is it possible that the information was never relayed back to [i]High Charity[/i], but I find it unlikely. More likely that the Hierarchs kept the information from being released.[/quote] You sir, have done a great job at explaining everything, even for me who read the books.

[quote][b]Posted by:[/b] fudgehog1925 [quote][b]Posted by:[/b] Herosmurff Do the covenant even know about the flood before Halo:ce?[/quote] No one did but the Forerunners.[/quote] Not true. It's been hinted at that the Covenant had at least a general-albiet flawed-understanding of the Flood prior to the opening of the Human-Covenant war. Most of their information, as far as we know, was based off of Forerunner inscriptions which they never fully comprehended. Basically, they knew that the Flood existed and that it was incredibly dangerous, but little more, and we've been given almost no evidence to suggest that the Covenant had met the Flood face-to-face prior to the events of Halo Wars. However, it is a FACT that the Covenant encountered the Flood during the events in that game. Is it possible that the information was never relayed back to [i]High Charity[/i], but I find it unlikely. More likely that the Hierarchs kept the information from being released.

[quote][b]Posted by:[/b] Herosmurff Do the covenant even know about the flood before Halo:ce?[/quote] No one did but the Forerunners.

[quote][b]Posted by:[/b] Rocko 1131 I didn't read the books, but in there does it say exactly why Reach was glassed? [/quote] Oh, sweet baby Jesus. The storyline weeps right now. To begin, the Covenant only partially glassed Reach, unlike almost every other human world that they came across. People who believe that Reach was fully glassed are either morons or inexperienced with the particulars of the story. [quote]Are the covenant just genocidal? I don't believe that. They are obviously a race of high intelligence and would need a solid reason to destroy an inhabitable planet.[/quote] The Covenant, at this point in the story, are entirely committed to burning humanity to the ground and making it look like they never existed. Why? The dudes in the floaty chairs with the pretty golden hats told them to. Sorta like when the Pope told the Europeans back in the tenth century that Muslims and Jews in Palestine were an affront to God and that they needed to be wiped out. The Covenant have declared a jihad/crusade/(insert your favored term for holy war here) against the human race. That is why they glass humans wherever they find them. The Covenant do run some ground operations for reasons that are never fully explained. My guess is that most ground operations are for the recovery of Forerunner artifacts, or to ensure that no Forerunner artifacts can be destroyed during glassing, like the Sigma Octanus IV theater which delivered the coordiantes for Installation 04 into the laps of both the Covenant and Cortana, or the ground operations on Reach which were supposed to recover the Forerunner crystal from the tunnels under CASTLE base. [quote]What if the covenant found the Flood on Reach? What if they were trying to contain infection and destroy the parasite? That would be an excellent reason to glass Reach. Reach is a big planet, and it would be difficult to check every single nook and cranny. The flood were probably there the whole time and the humans just never found them, but the covenant did and set out to exterminate the parasite.[/quote] First, if the parasite was on Reach it would've been inside a secure Forerunner facility, like on Installation 04, and the covenant will not destroy anything Forerunner willingly. Most would rather die than incur that kind of miasma. They consider it to be a sacrelige of the highest degree. That's why they boarded the [i]Pillar of Autumn[/i] above Installation 04 instead of burning it out of the sky-they didn't want to cause any damage to the ring. The only instance we have seen to the contrary is when the Abriter destroys the Forerunner research lab in Halo 2, and even that's kind of a grey area because he does so in an attempt to squelch heresey of an even higher order. I doubt the Hierarchs were upset about the Arbiter's methods considering the things the Heretic leader was saying. And if the Flood wasn't contained in anything, chances are it would've swallowed up Reach long before. [quote]Then war ensues because the humans don't like their home being destroyed, when in fact the covenant's motives were to destroy the Flood.[/quote] Now your timeline's completely out of whack, and it's not even because you haven't read the books. Did you completely skip Halo Wars as well? The Human-Covenant War began in 2525 at Harvest. Reach was attacked and partially([b][i][u]NOT FULLY[/u][/i][/b]) glassed in 2552. The war has been on for 27 years before Reach falls. So NO. [Edited on 01.22.2010 5:08 PM PST]

they did it becasue they needed to get new windows and they didnt want to spend any money. Are you happy [Edited on 01.03.2010 9:12 AM PST]

They had a war with humans and they thought it was our homeworld .

They did it because they view humans as not worthy of living. So they want to wipe them from existence. Just like the Catholics in Medieval Times!

Well, the particulars of the battle can be read about in Fall of Reach and First Strike; but to learn exactly why the Covenant is after Humanity in the first place, read Contact Harvest. I recommend all of the books, they make for an entertaining read.

no. just no.

the covenant didn't glass all of reach, they just glassed around 2/3 of it, on the rest of the planet they started digging for some foreunner object that makes slipspace travel.......loopier. but then the few spartans that were still on reach got to the stone first, and then, read the book First Strike to know more

[url=http://halo.wikia.com/wiki/Reach]here[/url] read away

[quote][b]Posted by:[/b] reptile1892 [quote][b]Posted by:[/b] Rocko 1131 Are the covenant just genocidal? I don't believe that. They are obviously a race of high intelligence and would need a solid reason to destroy an inhabitable planet. [/quote]1. The Covenant [i]are[/i] genocidal. 2. There was a Forerunner crystal on Reach. They wanted it. 3. Reach was a UNSC controlled planet. It was very far from uninhabitable. [quote][b]Posted by:[/b] Rocko 1131 Reach is a big planet, and it would be difficult to check every single nook and cranny. The flood were probably there the whole time and the humans just never found them, but the covenant did and set out to exterminate the parasite. [/quote]No. That's like saying "My property is pretty big, and it's hard to check everywhere, so there might be an elephant on it somewhere." I suggest you gain some knowledge on the subject before you come up with any more ideas. [/quote] 3. ? If I read correctly I believe that Rocko is trying to say why would the Covenant destroy a planet they could live on..then you go on to say the same thing in number 3. Not a big problem I just noticed it and questioned if I read it correctly.

because its faster to kill humans then having to send in 100,000s of troops to do it...duh

The prophets of Truth, Regret, and Mercy declared humanity a threat and that we are vermin that deserve nothing more than extinction. That is why the Covenant glass planets.