By chapter eight of George Orwell's Animal Farm, the pigs are firmly entrenched as the unequal leaders and primary consumers on the farm. The other animals are always hungry and overworked, but the pigs send Squealer to convince them, through various kinds of propaganda, that they are actually eating better and working less than they did when Jones was there. Of course that is not true, but most of the animals cannot remember that far back and eventually believe the persuasive pig.
One of the most consistent and successful strategies Squealer employs is blaming Snowball for things he of course did not do. This pig who can "turn black into white" generally uses Snowball as a diversion from something else that is happening on the farm or with Napoleon.
In this case, Napoleon publicly allied himself with Frederick and planned to do conduct business with him; however, rumors of Frederick's mistreatment of his own people have caused Napoleon to recant his position--and send Squealer to do damage control with the other animals.
Among the things, Squealer announces that Snowball is not the hero everyone remembers him being.
Snowball had never--as many of them had believed hitherto--received the order of "Animal Hero, First Class." This was merely a legend which had been spread some time after the Battle of the Cowshed by Snowball himself. So far from being decorated, he had been censured for showing cowardice in the battle.
Of course the older animals find this difficult to believe, as they remember fighting this battle with the heroic Snowball. (The readers remember it, too, so we know Squealer is lying.) Soon, though, Squealer is able to convince them that Snowball had been a coward, not a hero, at the Battle of the Cowshed.