The last episode of season three starts with the impossible: George has gotten laid. Unfortunately, his amorous conquests are the nieces of the Duke of Wellington, who has personally sworn to kill anyone who defiles one of his relatives. George is terrified of fighting the duel so Baldrick suggests he should get someone else to fight it for him, and suggests Blackadder, who of course, is not pleased. However, when he remembers his identical Scottish cousin, who just happens to be a homicidal maniac, MacAdder, is in town he changes his mind. Of course, MacAdder refuses to fight and Blackadder must pretend to be the prince and fight the duel himself. Wellington turns out to be a blustering idiot, and the duel turns out to be fought with cannons, and Blackadder is shot. But all is well! The cannon ball hit his cigarillo case, and everything is fine! George, pretending to be the butler, Blackadder, steps out of the shadows to reveal he is the prince, but Wellington shoots him in his anger. At that moment, the mad king appears, looking for his son, and Edmund, still in the prince's clothes, goes off with him, presumably to live the rest of his life as the Prince Regent.
But wait... George isn't dead after all! The bullet hit HIS cigarillo case—oh, wait, he must have left it on the dresser. Bugger.
- Anachronism Stew: Prince George references the story The Prince and the Pauper, whose author, Mark Twain, wasn't even born until 1835.
- Artistic License History: Done for comedic effect, but historically the person who was challenged (and not the challenger) was able to select the weapons used in the duel, unless the challenger was of higher social status. As Prince George was of higher social status than Lord Wellington he would have got to choose the weaponry instead of Wellington, whether challenged or challenger - and would likely not have chosen a cannon.
- Ax-Crazy: MacAdder. His plan for helping his cousin involves killing the prince.Edmund: He's mad. He's mad! He's madder than the mad Jack MacMad, the winner of last year's Mister Madman Competition.
- The Bad Guy Wins: An odd, yet awesome example of the trope. Blackadder may be the protagonist, but he's certainly a bad guy. And he gets to live out the rest of his life as the Prince Regent, and eventually the king, while George dies. However, it's awesome.
- Buffy Speak: One of the few times Blackadder is so mad he can't even think of a simile.Blackadder: We're about as similar as two completely dissimilar things in a pod.
- Can't Get Away with Nuthin': Prince George, who has had no luck with the girls throughout the series, finally gets laid. Twice. And is killed for it.
- Chekhov's Gun: The cigarillo case.
- The Coroner Doth Protest Too Much: Blackadder threatens to kill Baldrick by cutting him into thin strips and telling Prince George that he walked over an unusually sharp cattle grid while wearing an extremely heavy hat.
- Dreaming of Things to Come: Prince George claims to have had a dream of an eagle that flew around the room 3 times and got into bed with him, before turning into a large black snake and stealing all the covers.
- Duel to the Death: Prince George is challenged to one.
- Even Evil Has Standards: Blackadder may be very much a villain protagonist, but even he thinks that Wellington's punching George around is going too far. Though considering how Blackadder himself is only too happy to punch George when he and Wellington are discussing what is or isn't a hard hit, it's likely that he's acting out of empathy for Wellington's own servants rather than George.
- Or, Blackadder was trying to drag it out just to be a Jerkass to George.
- Every Man Has His Price: George is able to convince Blackadder to go back and fight the duel with copious amounts of bribery. Blackadder's response essentially epitomises this trope (and really sums up his entire character)...Blackadder: A man may fight for many things: his country, his principles, his friends, the glistening tear on the cheek of a golden child... But personally, I'd mud-wrestle my own mother for a ton of cash, an amusing clock and a sack of French porn! You're on!
- General Failure: Wellington, who believes war is about shouting and stations his men in Alaska to try and catch Napoleon in case he tries to sneak up on them. He actually seems competent enough the rest of the time however, unlike the generals seen in the next series.
- Hidden Depths: Not only is Macadder a fish salesman rather than a real warrior, he's apparently a very good salesman.
- Honor Before Reason: When Blackadder as the Prince proves to be quite intelligent, Wellington expresses regret that he needs to die. Once the duel is concluded and Blackadder survives, the Duke declares that honor is satisfied.
- Humiliation Conga: Having already offended Wellington when first meeting him, George manages to make things ten times worse by trying to sit down and discuss military strategy with him and Blackadder when he's just supposed to be serving them tea, causing Wellington to punch him to the ground. Then he gets smacked around another few times as Blackadder and Wellington discuss whether or not the latter hit George too hard. And then, as if it were possible, things go From Bad to Worse when it turns out that George has unwittingly served Wellington with coffee instead of tea...
- Large Ham: Wellington, and gloriously so.Wellington: THERE'S ONLY ONE WAY TO WIN A CAMPAIGN! SHOUT, SHOUT AND SHOUT AGAIN!Blackadder: So, you don't think inspired leadership, and sound tactical planning have anything to do with it?Wellington: (Beat) NO. IT'S ALL DOWN TO SHOUTING! BAAAA!
- Leaning on the Fourth Wall:Edmund: Yes, I'm afraid my ambitions stretch a little further than professional idiocy in West London. I want books written about me. I want songs sung about me. And then, hundreds of years from now, I want episodes from my life to be played out weekly at half past nine by some great heroic actor of the age.
Baldrick: (smiling) Yeah, and I could be played by some tiny tit in a beard.
- No-Sell: Wellington doesn't believe that George and Edmund switched roles.
- Not Even Bothering with the Accent: An odd inversion, as King George III speaks with a German accent, which there's almost no way that his real-life counterpart would have had. Then again, he is mad, so he may be affecting the accent as part of his illness.
- Not Quite Dead: Played straight when Blackadder gets a cannonball to the chest, as his cigarillo case cushions the impact and saves his life. Subverted when Wellington shoots George, as he too claims to have been saved by a cigarillo case, only to die permanently when he realises he forgot to bring it.
- Pocket Protector: Taken to comedic extreme. Blackadder's cigarillo case saves him from death by cannon fire.
- Prince and Pauper: Edmund and George switch coats and wigs and pretend to be each other. Lampshaded by George:George: This is just like that story, The Prince and the Porpoise.
Edmund: And the Pauper.
George: Of course. The Prince and the Porpoise and the Pauper.
- Puff of Logic: George doesn't notice he's dead until he realizes he forgot his cigarillo case.
- Record Needle Scratch: Sappy music plays as George and Edmund lay dying, and stops when they both sit up.
- Shout-Out to Shakespeare: When Prince George talks about a large eagle circling the room and Duncan's horses turning and eating each other, it is a reference to Macbeth.
- Small Name, Big Ego: MacAdder acts like the second coming of William Wallace, when he is in fact a fish salesman.
- Smart Ball: The three main characters are trying to come up with a plan to get the Prince Regent out of a duel he's sure to lose, when the plan comes up of Blackadder and the Prince switching places so that Blackadder can fight instead. When the Prince notes that it will never work, because "my portrait hangs on every wall", Baldrick - who thought to solve the problem of his mother's low roof by cutting off her head - offers up this gem:Baldrick: Well, my cousin Bert Baldrick, Mr. Gainsborough's butler's dogsbody, says that all portraits look the same nowadays since they're painted to a romantic ideal rather than as a true depiction of the idiosyncratic facial qualities of the person in question.Blackadder: (grudgingly impressed) Your cousin Bert obviously has a larger vocabulary than you, Baldrick.
- Take This Job and Shove It: After MacAdder bails on him, Blackadder flatly refuses to partake in the duel and gives George a serious piece of his mind.Blackadder: I'm afraid that the duel is off.George: Off?Blackadder: As in 'sod'. I'm not doing it!George: By thunder, here's a pretty game! You shall stay sir, and do duty by your prince, or I shall-
- Uncanny Family Resemblance: Blackadder and MacAdder. Everyone is astounded how alike they look!
- Violent Glaswegian: MacAdder.