When the Empire discovers the Rebel base on Hoth , Luke leads his squadron to battle a swarm of AT - AT Walkers .
The situation turns out to be serious enough that Luke and the others participating in the Hoth     have to retreat .
When the Empire discovers the Rebel base on Hoth , Luke leads his squadron to battle a swarm of AT - AT Walkers , but the situation turns out to be serious enough that he and the others participating in the Battle of Hoth have to retreat .