Napoleon uses Squealer as essentially the propaganda machine, the propaganda newspaper for the animals - to keep them in obedience.
Some more Squealer lies:
In order to explain why the pigs stole the milk, Squealer said the pigs are the brains behind the function of the farm and it has been scientifically proven that pigs work better with milk and apples. (Ch. 3)
In Chapter 5, Squealer tells the animals that Snowball was not a hero in the first farm defense. In Chapter 6, Squealer convinces the animals why the pigs dignity requires they sleep in the farmhouse.
It is also later revealed that Squealer may have been the one altering the commandments.
We can assume that the sentiments that Snowball has been frequenting the farm at night, dumping over milk pails, breaking eggs, trampling the seed-beds and chewing the bark off the trees are lies.
Squealer indeed states that
Snowball was in league with Jones from the start.He was Jones' secret agent all the time. It has been proved by documents which he left behind him an dwhich we have only just discovered.
This leads the insightful reader to conclude this is just propaganda and these documents are newly created.
There are a lot of things that Squealer does to throw mud on Snowball after Snowball is gone. Let us look at a couple of examples from Chapter 6.
The first thing is when he claims that Snowball had spread lies and that these lies were the only thing that made the animals think Napoleon had been working on trading with people. This was a lie.
Perhaps the biggest lie is the one where Squealer claims that it is Snowball who destroyed the windmill. He said Snowball snuck back onto the farm and destroyed it. This is another lie.