What happens to Boxer in Animal Farm? How are these events ironic?

is sent to the knackers to be slaughtered.  It is ironic because it was
one of the abusesaccused humans of perpetrating against animals.

Old Major sells the animals on a dream of equality and opportunity.  In his vision, no
animals will ever be held hostage to humans.  Animals will work together to create anof
cooperation and comfort.

It does not take long for the dream to sour.  As
soon as the animals kick the humans off the farm, the pigs take charge.  From that point on,
they slowly gain more and more power at the expense of the other animals.

One
of the promises made to the animals is that once they were too old to work, they would be able
to retire.  Humans would have killed them, but inthey would be blessed...