''Three Hearts And Three Lions'' is a fantasy novel by Creator/PoulAnderson.

During WorldWarII, Holgar Carlsen is in Denmark, part of LaResistance. Except that at one crucial moment, he finds himself transported to a fantasy world, where the Matter of France from ChivalricRomance, Charlemagne and his paladins, is true. And that he has some sort of connection with this world that he can not remember. He has a pile of armor, and a steed, waiting for him.

A major influence on DungeonsAndDragons.

Creator/RandallGarrett wrote a pun-filled {{Filk}} version of the novel, with Poul's approval.

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!!Tropes found in this work
* AllTrollsAreDifferent: ''Three Hearts and Three Lions'' is, if not the source of the regenerating troll concept, at least one of the earliest known examples.
* AnimatedArmor: Guarding the passes into fairyland.
* BadassBookworm: Holger, in both worlds.
* ChickMagnet: Holger, to his surprise. Apparently he never got that lucky back home.
* ChosenOne: Martinus hypothesizes that Holger is this.
* CrushBlush: While dealing with a forward fairy.
* {{Curse}}: Mother Gerd tried one, in the backstory.
* DealWithTheDevil: It's implied that Morgan le Fay has done this, even going so far as to help teach some local barbarians [[DemonLordsAndArchdevils demon worship]], [[HumanSacrifice the Black Mass complete with sacrificing infants]], and [[ImAHumanitarian cannibalism]].
* DoorstopBaby: Holger again. Also Alianora
* TheFairFolk: Complete with the allergy to cold iron and holy names.
* FireKeepsItDead: Holger and friends are fighting a troll, which keeps regenerating until they finally figure out to burn the bits they chop off. This book is the reason it works that way in ''D&D''.
* HumanSacrifice: To a nixie, and in a descrecrated church.
* IneptMage: Mother Gerd
* KillItWithFire: Perhaps the TropeMaker for trolls' vulnerability to fire.
* KnightInShiningArmor
* LeaveYourQuestTest: MorganLeFay appeals to him, more than once.
* LoveTriangle: Resolved fairly quickly.
* NiceToTheWaiter: Alianora rescues Hugi
* TheNoseKnows: Hugi
* ObliviouslyEvil: The nixie
* OrderVsChaos: a TropeCodifier
* OurSoulsAreDifferent: Not all of us have got them.
* ThePaladin: The paladins of this work are where the original inspiration for the Paladin class from ''DungeonsAndDragons'' came from.
* RaisedByWolves: Or rather, by dwarves.
* SendMeBack: Holger is suddenly switched out from the climactic battle against evil back to our Earth, where he appears in the middle of a firefight with Nazis. It's ''suggested'' that the battles are connected, and that good triumphed back in the alternate reality, but Holger would like to know for sure.
* ShapeshiftingLover: Alianora
* SummoningRitual: Mother Gerd says she summoned a sprite.
* SwansASwimming: Alianora is a swanmay
* TakenForGranite: The Giant.
* {{Unicorn}}: Alianora has one for a whilte
* WickedWitch: Mother Gerd
* YearOutsideHourInside: The elf hill.
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