"Hasten, hasten, best of horses! Oh, run, my comrade, run as no horses ever did erenow, for surely all men are pursued with us. Haste thee, my darling, for we ride against striding Time, we ride against marching Chaos. Ah, God be with thee, God strengthen thee to run!"
'Three Hearts And Three Lions' is another charming and hugely influential Poul Anderson fantasy. While it lacks the strum und drang atavistic intensity of 'The Broken Sword', much of that book's invention and storytelling deftness is on display here. Whereas 'The Broken Sword' is fully emerged in its brutal Fantasy world of vengeful doomed Vikings and manipulative gods and elves, in 'Three Hearts And Three Lions' Anderson uses a modern day viewpoint character who is swept into a magical realm, who acts as a viewpoint character for the audience. Holger Carlsen is an affable everyman who finds himself transported into a different world where it seems like he is destined to play a key role. As such he's the ancestor of all the subsequent modern day viewpoint characters thrust into fantastical situations they don't understand, from Michael Moorcock's Erekose to Stephen Donaldson's Thomas Covenant, and 'Three Hearts And Three Lions' has provided a blueprint for subsequent variations and deconstructions of the chosen one story.
Holger Carlsen is a Danish engineer who, during World War II, is hit by a shell and wakes up naked in a forest, in a world where it turns out that magic is very much real, elves, trolls and giants exist alongside the legends of our world, and the history of our world is just myths and legends. Carlsen finds that he is the knight of Three Hearts and Three Lions, a figure that appears to be of great importance in this world. Duke Alfric and Morgan le Fay, the leaders of the Faeries, are incredibly keen to have him either killed and out of the way, whilst a Saracen is looking for him. With the help of Hugi the dwarf and Alianora the swan-may, Carlsen goes in search of the sword Cortana, which is tied with his destiny as the knight of Three Hearts and Three Lions, and may have the power to send him home.
Anderson uses Carlsen as a viewpoint character, through which the audience gets to vicariously experience the wonder and confusion of being plunged into a strange and fantastical world. However, while characters such as these can make an easy entry point for the reader into what might otherwise be a strange and disorientating world, they also run the risk of being so much of a blank slate that they come off as bland, or worse, as a wet blanket, oblivious to the wonders around them as they try desperately to get back home to rural Kansas. Anderson avoids this quite elegantly and inventively. Carlsen's stolid engineer's mind allows him to succeed as a knight by coming up with very modern and practical solutions to the fantastical challenges that face him. So he defeats a dragon not by expertise with a sword, but by using cold water to make it overheat like a boiler, and he works out that the curse of the troll's gold is caused by the radiation released when the carbon in the troll turns to silicon when it turns to stone in the sun.
This rationalism extends to Calrsen's ontological understanding of the fantasy world he finds himself in. Calrsen theorises that, as quantum theory allows for an infinite number of alternate universes, it's possible that a universe exists in which all the myths and legends of our world are fact, and magic exists as a physical force, and that he has somehow been transferred across the boundaries between alternate realities. Michael Moorcock would later develop this idea as the basis for the multiverse, the ever shifting alternate realities through which the Eternal Champion wanders. It's interesting that a writer like Anderson who is so adept at writing wonderful fantasy stories should be so concerned with rationalising them, perhaps coming from his need as a writer of hard SF to make sure the worlds in his writing follow the laws of physics, and have vaguely plausible excuses for when they don't. Rather than making his fantasy world less magical, the fact that the non-magical aspects of the world are so realistically rendered makes the fantastical aspects of the world more believable.
'Three Hearts And Three Lions' also presents another idea that would provide a cornerstone for Moorcock's Eternal Champion series, namely that of the eternal struggle between the forces of Law and Chaos. In Anderson's book, Law, as represented by humanity and Christendom, is under threat by the forces of Chaos, as represented by the forces of Faerie, which is mirrored by the conflict between the Allies and the Nazis in our universe. While the idea has the seeds of its origin here, Moorcock would go on to develop the idea of the balance between Law and Chaos more fully in his work. In 'Three Hearts And Three Lions', Law is basically the equivalent of good, whilst Chaos is evil. In Moorcock's work, neither Law or Chaos is good or evil in and of itself; they are two natural forces that need to be in equilibrium, and evil arises when there is an imbalance in either direction. This allows Moorcock to fully explore the nuances only hinted at in Anderson's work.
Moorcock would later echo Carlsen's fate with that of Erekose. Carlsen discovers his identity as the knight of Three Hearts and Three Lions is that of Holger Danske, a knight of Arthur's round table who returns during times of chaos to save the world. Having saved humanity from the encroaching forces of Faerie, he is whisked back to our world where he helps to defeat the Nazis. But this means he is separated from his love, Alianora, as Erekose is from his love Erminzhad, and he is destined to search for a way to travel across alternate universes to find her again.