Mr. Frederick owns the neighboring farm of Pinchfield. He may be a human farmer, but he's no drunk idiot like Mr. Jones: he's "a tough, shrewd man, perpetually involved in lawsuits and with a name for driving hard bargains" (4.2).
He's also a symbol for Hitler.
At first, Frederick is a little worried that the Rebellion will spread to other farms, so he goes on the attack by spreading rumors that the "animals there practiced cannibalism, tortured one another with red-hot horseshoes, and had their females in common" (4.3).
Unsurprisingly, the animals on Frederick's farm never rebel. Also unsurprisingly, the pigs don't get along to well with him. Inter-farm relations are frosty for much of the story, and one of Squealer's jobs is to spread the rumor that Snowball is conspiring against Animal Farm with Frederick.
And then there's a surprise twist. Napoleon needs to sell a pile of lumber. After he promises it to Pilkington, however, he does a switcheroo and decides to sell it to Frederick, instead. The reason (according to Squealer)? He was playing the two farmers off each other to drive up the price. But Frederick has a trick up his sleeve: Mr. Whymper comes running back to tell Napoleon, "The bank-notes were forgeries! Frederick had got the timber for nothing!" (8.14).
Oops. Looks like the player got played.
The whole timber debacle is a stand-in for Stalin's non-aggression pact with Hitler, signed in 1941. (For more on why Stalin should have hated Hitler, check out our "Character Analysis" for Mr. Pilkington.) The pact allowed former bitter enemies Soviet Russia and Nazi Germany to slice up Eastern Europe into spheres of influence. (Too bad for the poor people of Eastern Europe, now doomed to domination by one totalitarian regime or the other.)
This whole alliance thing between Stalin and Hitler really got Great Britain feeling nervous. Through most of 1940 and 1941, Britain was fighting Germany in World War II all by its lonesome, since France had crumbled in June 1940 and the U.S. didn't enter the war until December 1941. The prospect of a united Germany and Soviet Union… well, let's just say that more than one British official probably had to change his pants when he found out about that.
But the Nazi-Soviet agreement didn't last. Just like Mr. Frederick, Hitler broke the pact. In 1941, Germany launched Operation Barbarossa, a massive surprise attack into Soviet territory. By December of 1942, German troops were within 20 miles of Moscow—and only a heroic (and bloody) effort by the Soviet Red Army finally pushed them back.
In Animal Farm, the Battle of the Windmill is a miniature version of this war on the Eastern Front. (Quick Brain Snack: fighting in Western Europe was on the Western Front; fighting in Eastern Europe was fighting on the… wait for it… Eastern Front.) Frederick and his men advance and blow up the windmill, but the animals end up driving them out. After that, Frederick disappears from the story—and good riddance.