Three Hearts and Three Lions

Three Hearts and Three Lions (1961) is classic fantasy novel written by Poul Anderson. It is also the very first book in the Appendix N - for alphabetical reasons, but still hugely influential to D&D (and to Michael Moorcock, one of my fantasy writers, also in the appendix N) . It is the main source of the original idea of alignment, and probably where D&D paladins and trolls come from.

It is also a great book, well worth the read, even if you're not exploring the origins of D&D.

The book tells the story of Holger Carlsen, a Danish engineer that gets transported from World War II (where he is fighting Nazis) to another universe. Here, there is another war going on: between the forces of Law and Chaos. Chaos is comprised of elves, fairy, sorcerers and trolls, while Law is in need of a true champion - who might be Holger himself.

From there on, Holger spends most of the book travelling around with two local companions (a dwarf and a "swan maiden"), going through many adventures that are only barely connected (often verging on the picaresque), and trying to find a reason for his predicament, a way to get back to his own world, or both. There is magic, dragons, giants, and magic swords - drawing upon German and English myths, Dunsany, Tolkien (the "riddle" scene seems to be lifted almost entirely from the Hobbit), Shakespeare, etc. This is traditional fantasy - at its best.

Most of the book has a bit of a "young adult" vibe. It feels shallow (and a bit slow) at first, but pleasing to read, with loads of humor, adventure, romance, and so on. It takes a deep dive by the end of the book, making the journey exponentially more interesting. Some people will find the ending a bit abrupt, but for me, once we can see the whole picture, there is no further need to expand on the details of Holger's story.

In short, this is a classic. It doesn't quite reach the "favorite" level for me (which includes Tolkien, Moorcock, Dunsany, Poe, Lovecraft and GRRM), but it certainly belong in the top fantasy classics, well above average even for the Appendix N. 

When I finished reading, I immediately picked "The Broken Sword", which has a different tone altogether - more bloody, epic, and tragic. If you prefer that to this adventurous vibe, it is also worth the read (and probably a review of its own somewhere along the line).

Note: the book apparently has too versions. This is from mine: