The Two Generals’ Problem

Time to tell a narrative about idempotency, computer technology, and the Night of the Multiple Orders. • Backed by Dashlane —try 30 days for free at:

Authored by Sean M Elliott and Tom Scott
Directed by Tomek
Graphics by Mooviemakers
Audio mix by Haerther Productions

Thanks to Dashlane for supporting the video clip! Get a 30-day free trial at


  1. Yes, I had help with the graphics for this series. There’s no way I’d have animated that myself! On that note, thanks to Dashlane for sponsoring and helping me hire an animator: their free trial link is

    • @Hannah If the server sees a duplicate idempotency token, it should send a message to you to verify your intension (ideally through an alternative messaging mechanism) rather than just throwing the second order away.

    • @Bruno Signori Wustro NP Complete

    • Bruno Signori Wustro

      @Tad Richard thats great, i have a college assignment where i have to implement a metaheuristich method on a NP problem in order to find a “good” solution and this looks like a good one, im already excited. Thanks for replying.

    • The animations looked great! Money well spent.

    • That One Creative Username

      How is this two weeks ago

  2. I’ve been in meetings where managers (without much experience) are trying to design things on the fly. Best you can do is bring up things like this to stop them, or at least attempt to slow them down. Communication theory is its own field.

  3. On a side note: I just read the news that Deliveroo is going to stop their business here in Germany this Friday. That timing of the video… 😉

  4. Surprised a castle built in a valley could even take on one army. Build a couple catapults and pummel the fortress from above. Surely the other general will see the army’s catapults destruction and do the same. Just my idea though 🙂

  5. That Dashlane seems a bit suspicious to me! A password management system that requires a subscription? What if you stop the subscription? Do you lose access to your passwords? Sounds extortionate! :/

  6. over00lord Unknown

    6:11 “Next time I’ll just cook for myself”
    I was REALLY a hoping that the sponsor for this video would’ve been Hello Fresh.

  7. sanderwasalbezet

    We can thank Satoshi Nakamoto for solving this, also called the Byzantine generals problem. Bitcoin to the moon!

  8. Or, for a restaurant like a pizza place, just call them on the phone if you have any problems with their web app. Computer programs are apparently really hard to do well. There are tons of bugs constantly in services offered over the web, even when what they are offering are courses on how to configure computers and build web sites. Some people are really good at this computer stuff, but the vast majority of people working on it really aren’t those people. That’s my opinion.

  9. Micheal Thatcher

    27th on trending.
    27 thousand likes.
    Coincedence? I think not.

  10. For the general problem what about this?

    General A sends a message saying, at 8PM we both move back to see that you recieved this message, at 8:15PM if you see the movement, strike. This would work because if you don’t see movement at 8PM, the messenger was killed, and if you see movement, then you know to strike together at 8:15PM

    What’s the problem with this solution?

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