Ender tried to grasp the amounts of time that had gone by. "And the ships have been traveling for seventy years—"

 

"Some of them. And some for thirty years, and some for twenty. We make better ships now. We're learning how to play with space a little better. But every starship that is not still under construction is on its way to a bugger world or outpost. Every starship, with cruisers and fighters tucked into its belly, is out there approaching the buggers. Decelerating. Because they're almost there. The first ships we sent to the most distant objectives, the more recent ships to the closer ones. Our timing was pretty good. They'll all be arriving in combat range within a few months of each other. Unfortunately, our most primitive, outdated equipment will be attacking their homeworld. Still, they're armed well enough — we have some weapons the buggers never saw before."
_{Ender's Game - Chapter 13}

And then the order came, the final mad assault on the planet's surface, the detonation of the M.D. device, the disintegration of the entire world.

 

Victory.

 

They celebrated. They drank. They wept for joy. They remembered all the people back on Earth that once upon a time they knew and loved, and wept again in grief. For by now they were all forty years older, and before this fleet could return eighty years would have gone by.

 

But they weren't going home. They had never planned to. Knowing what relativistic space travel would do to them, that they could never return to the lives they had once had, they set out on this expedition knowing that if they won, it would cease to be a military fleet and become, all at once, a colony.

 

They had expected to have to fight for control of the planet's surface, and it was to be a mission of extermination, like the one the Formics had launched against Earth. But after that last battle, it wasn't necessary. The queens of all the conquered worlds had been gathered together on the last planet. All their eggs in one basket, so to speak. When they died, the workers and larvae on all the worlds died with them. Not immediately, but within hours or days.
_{"The Goldbug" (short story)}

Why should I be stuck now with decisions carelessly made twenty-four years ago? What I've written since is right; those contradictory but unimportant details in the original novel are wrong.

 

Therefore I have rewritten chapter 15 of Ender's Game, and at some future date there will be an edition of the novel that includes the revised chapter.
_{Ender in Exile - Afterword}

Ender tried to grasp the amounts of time that had gone by. "And the ships have been traveling for seventy years—"

"Some of them. And some for thirty years, and some for twenty. We make better ships now. We're learning how to play with space a little better. But every starship that is not still under construction is on its way to a bugger world or outpost. Every starship, with cruisers and fighters tucked into its belly, is out there approaching the buggers. Decelerating. Because they're almost there. The first ships we sent to the most distant objectives, the more recent ships to the closer ones. Our timing was pretty good. They'll all be arriving in combat range within a few months of each other. Unfortunately, our most primitive, outdated equipment will be attacking their homeworld. Still, they're armed well enough — we have some weapons the buggers never saw before."
_{Ender's Game - Chapter 13}

And then the order came, the final mad assault on the planet's surface, the detonation of the M.D. device, the disintegration of the entire world.

Victory.

They celebrated. They drank. They wept for joy. They remembered all the people back on Earth that once upon a time they knew and loved, and wept again in grief. For by now they were all forty years older, and before this fleet could return eighty years would have gone by.

But they weren't going home. They had never planned to. Knowing what relativistic space travel would do to them, that they could never return to the lives they had once had, they set out on this expedition knowing that if they won, it would cease to be a military fleet and become, all at once, a colony.

They had expected to have to fight for control of the planet's surface, and it was to be a mission of extermination, like the one the Formics had launched against Earth. But after that last battle, it wasn't necessary. The queens of all the conquered worlds had been gathered together on the last planet. All their eggs in one basket, so to speak. When they died, the workers and larvae on all the worlds died with them. Not immediately, but within hours or days.
_{"The Goldbug" (short story)}

Why should I be stuck now with decisions carelessly made twenty-four years ago? What I've written since is right; those contradictory but unimportant details in the original novel are wrong.

Therefore I have rewritten chapter 15 of Ender's Game, and at some future date there will be an edition of the novel that includes the revised chapter.
_{Ender in Exile - Afterword}

They colonized the abandoned Bugger planets

And then the order came, the final mad assault on the planet's surface, the detonation of the M.D. device, the disintegration of the entire world.

They had expected to have to fight for control of the planet's surface, and it was to be a mission of extermination, like the one the Formics had launched against Earth. But after that last battle, it wasn't necessary. The queens of all the conquered worlds had been gathered together on the last planet. All their eggs in one basket, so to speak. When they died, the workers and larvae on all the worlds died with them. Not immediately, but within hours or days.
_{"The Goldbug"}

Note that this was a retcon, as in Ender's Game itself the fate of the surviving fleet isn't given, and they aren't on the planet when Ender comes. However, all works written since The Goldbug have adopted this retcon, (including Ender in Exile, Ender's Game Alive, and "Governor Wiggin") and Card plans to change that chapter of Ender's Game whenever he gets around to publishing his "reconciled edition".

When I wrote the novel Ender's Game back in 1984, my focus in the last chapter, chapter 15, was entirely on setting up Speaker for the Dead. I had no notion of any sequel between those two books. So I was rather careless and cavalier with my account of Ender's time on the first colony. I was so careless I completely forgot that on all but the last formic planet, there would have been human pilots and crew left alive. Where would they go? Of course they would begin colonizing the formic worlds. And those who sent them would have at least allowed for that possibility, sending people trained to do whatever jobs they anticipated would be necessary. _{Ender in Exile - Afterword}

The International Fleet was dispatched long before the book starts, and was sent to many different planets

Immediately after the second invasion, the IF began sending out ships, timed so that they would all reach their destination at the same time. It is this fast approaching time window that Mazer was referring to.

Ender tried to grasp the amounts of time that had gone by. "And the ships have been traveling for seventy years—"

"Some of them. And some for thirty years, and some for twenty. We make better ships now. We're learning how to play with space a little better. But every starship that is not still under construction is on its way to a bugger world or outpost. Every starship, with cruisers and fighters tucked into its belly, is out there approaching the buggers. Decelerating. Because they're almost there. The first ships we sent to the most distant objectives, the more recent ships to the closer ones. Our timing was pretty good. They'll all be arriving in combat range within a few months of each other. Unfortunately, our most primitive, outdated equipment will be attacking their homeworld. Still, they're armed well enough — we have some weapons the buggers never saw before."
_{Ender's Game - Chapter 13}

The vast majority of these ships survived. Even in the last battle where all of the fighters had been killed, the starships still survived.

Only at the very periphery of the simulator did the M.D. field weaken. Two or three enemy ships were drifting away. Ender's own starships did not explode. But where the vast enemy fleet had been, and the planet they protected, there was nothing meaningful. A lump of dirt was growing as gravity drew much of the debris downward again. It was glowing hot and spinning visibly; it was also much smaller than the world had been before. Much of its mass was now a cloud still flowing outward.
_{Ender's Game - Chapter 14}

Their fate wasn't discussed in Ender's Game itself, but later works show that they went on to colonize the bugger homeworlds, and did not return to earth.

This was first shown in "The Goldbug" comic, but has since also appeared in Ender in Exile, Ender's Game Alive, and the two short stories, "The Goldbug", and "Governor Wiggin".

And then the order came, the final mad assault on the planet's surface, the detonation of the M.D. device, the disintegration of the entire world.

They had expected to have to fight for control of the planet's surface, and it was to be a mission of extermination, like the one the Formics had launched against Earth. But after that last battle, it wasn't necessary. The queens of all the conquered worlds had been gathered together on the last planet. All their eggs in one basket, so to speak. When they died, the workers and larvae on all the worlds died with them. Not immediately, but within hours or days.
_{"The Goldbug" (short story)}

This led to some minor inconsistencies with the last chapter of Ender's Game

When I wrote the novel Ender's Game back in 1984, my focus in the last chapter, chapter 15, was entirely on setting up Speaker for the Dead. I had no notion of any sequel between those two books. So I was rather careless and cavalier with my account of Ender's time on the first colony. I was so careless I completely forgot that on all but the last formic planet, there would have been human pilots and crew left alive. Where would they go? Of course they would begin colonizing the formic worlds. And those who sent them would have at least allowed for that possibility, sending people trained to do whatever jobs they anticipated would be necessary. _{Ender in Exile - Afterword}

Card says that he'll eventually change the passage in the future editions of the novel.

Why should I be stuck now with decisions carelessly made twenty-four years ago? What I've written since is right; those contradictory but unimportant details in the original novel are wrong.

Therefore I have rewritten chapter 15 of Ender's Game, and at some future date there will be an edition of the novel that includes the revised chapter.
_{Ender in Exile - Afterword}