Hoth is a remote ice planet and has a secret rebel base during the Galactic Civil War. It is inhabited by creatures, like Tauntauns and Wampas. The Rebel Alliance set up a base there until the Galactic Empire discovered their location, forcing the rebels to flee and abandon their base.
Background
Hoth is the sixth planet in the system of the same name. After the Battle of Yavin, Luke Skywalker proposed Hoth as the Rebel Alliance's new main base of operations after they evacuated their base on Yavin 4. The Alliance leaders agreed and Echo Base became the new Rebel base. To prevent the risk of total destruction that the Alliance faced during the Battle of Yavin, Luke also set up an evacuation protocol that stated that the base should be evacuated as soon as it was discovered by the Empire, in an effort to mitigate the effects of the inevitable counterattack.
Three years after the Battle of Yavin, Darth Vader learned what sector the base was in and sent Imperial probe droids to search for it. When one of the droids landed on Hoth, Luke spotted it, but his ambush by a Wampa ensured that the Probe remained undiscovered until it was too late because by the time Han Solo discovered and destroyed it the droid had already found the base and the Rebels suspected that the Empire knew where they were and initiated Luke's evacuation protocol.
The Rebels' fears proved correct: Before its destruction, the droid transmitted its finding to Death Squadron, the personal armada of Darth Vader. Captain Firmus Piett realized that the probe had found the Rebel base. Death Squadron's commander, Admiral Kendal Ozzel, dismissed the report as a smuggler's settlement, but Darth Vader confirmed otherwise and ordered Ozzel to set course for Hoth. Vader originally planned for Death Squadron to arrive at the edge of the Hoth system and use the system's asteroids to conceal the armada's arrival. Upon arriving, Death Squadron would initiate orbital bombardment to destroy the base and flush out the Rebels where they would be captured by General Maximillon Veers, the commander of Death Squadron's ground forces. However, Ozzel thought it was wiser to exit light speed as close to the planet as possible to catch the Rebels by surprise and had the fleet do precisely that. This proved to be a mistake because he brought the fleet too close within the base's sensors which alerted the Rebels to the armada's arrival causing them to raise an energy shield powerful enough to protect the base from orbital bombardment. Furious, Vader executed Ozzel for his blunder and promoted the more cautious Piett to Admiral and made him Commander of Death Squadron.
Veers and his troopers were then deployed for a surface attack. Led by Luke Skywalker, Rouge Squadron flew out in snowspeeders to hold Veers' forces off while the rest of the evacuation took place and even managed to down a few of the AT-ATs. However, because of the sheer might of Death Squadron, Veers was able to take out Echo Base's shield generator allowing Vader and the 501st Legion to overrun the base. The Battle of Hoth was a major Imperial victory that turned the tide in the favor of the Empire for the next six months however because of Luke's evacuation protocol, Ozzel's blunder, and Echo Base's Ion Cannon seventeen transports worth of soldiers, personnel, and equipment were able to escape the base's destruction.
Hoth on Wookieepedia: The Star Wars Wiki
