what happens to boxer and how do the other aniaml learn of his fate ?how do htey come to a final comclusion about these events?
Boxer is the true believer in Animal Farm and works harder than any of the other animals to make the farm a success. When the animals first take over the farm, he gets up a half hour before the rest of them to start working. His dedication motivates the other animals. He also lends crucial support to Napoleon, deciding that what Napoleon says must be true.
One of the initial promises of Animal Farm is that the animals will be given a retirement pension and not worked until they collapse and then be sold to the glue factory. That was what Farmer Jones did. Although no animal has ever received a retirement pension, when Boxer turns 12 and starts to feel old, he and the other animals are still hopeful:
. . . of late the subject had been discussed more and more. Now that the small field beyond the orchard had been set aside for barley, it was rumoured that a corner of the large pasture was to be fenced off and turned into a grazing—ground for superannuated [retired] animals. For a horse, it was said, the pension would be five pounds of corn a day and, in winter, fifteen pounds of hay, with a carrot or possibly an apple on public holidays.
When Boxer collapses at the end of the book, he thinks he will be allowed to retire and to have Benjamin retire with him as a companion. Instead, the pigs send him off to the glue factory. The animals see Boxer going off in the van. They are told he is going to the hospital, but Benjamin tells them the words on the side of the van indicate he is being taken to the glue factory to be killed. The animals run after the van and shout to Boxer to escape. He tries to kick his way out, but can't.
Later, Squealer tells the animals that it was a false rumor that Boxer went to the glue factory. The ambulance that took him to the glue factory had just been bought from the knackers and the old sign on its side not yet painted over. Squealer explains that Boxer actually had good care in the hospital. The animals believe this story and are relieved.
Of course, the story is a lie. Orwell is warning people not to be as gullible as the animals.
Late one night Boxer went out alone to drag a stone from the pile to the windmill and he collapsed. Two pigeons delivered the news to the other animals. When the others approach him he is lying on his side and he is having difficulty breathing. He tells the animals that it's his lung and that he's actually glad because he had been looking forward to finally getting to retire. Napoleon insisted that Boxer be taken to the hospital. When the truck arrived Benjamin finally speaks up and says they are all fools because the side of the truck says, "Alfred Simmonds, Horse Slaughterer and Glue Boiler, Willingdon. Dealer in Hides and Bone-Meal. Kennels Supplied." The animals decide, with Benjamin's help that they are taking Boxer to "the knackers" to be slaughtered.