[1] In the series, main character Taran matures from an impulsive and childish Assistant Pig-Keeper to a colleague and counselor of kings.

While Alexander's experience in World War Two informs the Prydain series as a whole, some specific instances inspired events in The High King.

[3] The action near Luneville, as well as the general icy and snowy conditions, caused Alexander great discomfort and served as direct inspiration for the episode.

Hen Wen delivers a cryptic prophecy and her oracular letter sticks shatter as she is revealing it, rendering her functionally mute.

He orders Smoit and Fflewdur to raise armies in their lands and among their allies while Taran, Coll, Gurgi, and Eilonwy go to bring the Free Commots to the banner of the Sons of Don and Gwystyl rouses the Fair Folk.

Gwydion himself heads to Caer Dathyl and sends messages to King Pryderi of the West Domains and other leaders to alert them of the war.

Meanwhile, unbeknownst to the heroes, Taran's crow Kaw reports to Medwyn, who begins organizing the animals to aid the resistance to the Death Lord.

Eilonwy's tapestry of Hen Wen becomes Taran's banner of the White Pig as they, Gurgi, and Coll collect the men and boys of the Free Commots in the army, including lucky Llonio.

His army is repulsed at the cost of the lives of many, including Llonio and the High King Math, and the Cauldron-Born manage to force the Sons of Don into hiding in the mountains.

In the midst of a snowstorm that threatens to kill the companions, Fflewdur sacrifices his magical harp to start a life saving fire.

Upon the victory over Arawn, Dallben, Gurgi, and the surviving Sons of Don (including Eilonwy and Fflewdur) prepare to leave for the Summer Country.

One contemporary review, by Houston L. Maples, noted that "the [novel's] bald appeal to juvenile risibilities is, in the end, rather too calculated, and inconsistent with the eloquence and grandeur of the best episodes.

"[6] Robert Ostermann, writing in The National Observer, said that Alexander's "kingdom and annals of Prydain are so complete, so compelling, that the reader leaves them for the last time with genuine regret.

"[8] In a retrospective essay about the Newbery Medal-winning books from 1966 to 1975, children's author John Rowe Townsend wrote, "Yet when every allowance has been made, one faces, reluctantly, the fact that the Prydain saga, with its constant anachronism, its slack repetitive action, its cast of two-dimensional figures and failure to compel serious belief, is not a satisfying epic; not, I believe, a front-rank work.

Writing for the Children's Literature Association Quarterly, Rona Glass contrasted it negatively with A Wrinkle in Time's depiction of gender relations.

In her view, "Alexander has created a strong female of brave behavior [Eilonwy], scarcely a stereotype, but he allows Taran to treat her as if she were one...