Animal Farm opens with a bang: "Mr. Jones, of the Manor Farm, had locked the hen-houses for the night, but was too drunk to remember to shut the popholes" (1.1).
Great. Mr. Jones is drunk, cruel, and an awful leader. When he's run off the farm, it seems like it's mostly his own durn fault. (Truth: we might have cheered.)
The Joneses are stand-ins for the last tsar of Russia, Nicholas II, and his wife, Alexandra. Nicholas II wasn't a drunk—at least, not that we know of—but he was an unpopular leader who was out of touch with his people and maybe not that interested in ruling them, anyway. It didn't help his popularity that he let Russia get dragged into World War I—and then did a bad job of managing it.
In February 1917, workers began to strike in Moscow. Nicholas sent the military in to suppress the people, but—surprise, surprise!—the military men refused to fire. Many of them actually joined the protestors. Eventually, Nicholas, his wife, and all their kids were packed off to the town of Ekaterinburg, and the Bolshevik party took over. (The story has a gruesome twist: eventually, Nicholas and his family, along with a few of their servants, were executed in the basement of their house.)
Mr. Jones may not be a tsar, but he has all of Nicholas II's incompetence and negligence: first, he comes back drunk from the Red Lion pub and forgets to feed the animals, and then he tries to whip the animals into submission. It doesn't work. They kick Jones out and, with the pigs at the head, tear through the farmhouse, destroying "the last traces of Jones's hated reign" (2.13)—just like the post-Revolution destruction of cultural objects.
Luckily, Jones doesn't suffer Nicholas's bloody fate. Instead, he spends most of his time in the Red Lion "complaining to anyone who would listen of the monstrous injustice he had suffered in being turned out of his property by a pack of good-for-nothing animals" (4.2). The other men aren't exactly sympathetic, but they are afraid that their own animals will catch the rebellion—that's why they help him at the Battle of the Cowshed.
This Battle tells us that Jones isn't just a symbol for old Nick; he's also a symbol for bosses in general. He represents an entire way of thinking—everything that the Bolsheviks aimed to overthrow in 1917. That's why he's such an effective tool of propaganda for the pigs. Whenever Squealer has to justify a hard decision, he asks the other animals, "Surely there is no one among you who wants to see Jones come back?" (3.14).
And what can they say to that?