Charles Williams, like his friends CS Lewis and JRR Tolkien, knew that pre English history, the Grail and the Arthurian and legends were and are real, true and important.
Taliessin through Logres
"Recalcitrant tribes heard;
orthodox wisdom sprang in Caucasia and Thule;
the glory of the Emperor stretched to the ends of the world.
In the season of midmost Sophia
the word of the Emperor established a kingdom in Britain;
they sang in Sophia the immaculate conception of wisdom.
Carbonek, Camelot, Caucasia,
were gates and containers, intermediations of light;
geography breathing geometry, the double-fledged Logos.
II
The blind rulers of Logres
nourished the land on a fallacy of rational virtue;
the seals of the saints were broken; the chairs of the Table
reeled.
Galahad quickened in the Mercy;
but history began; the Moslem stormed Byzantium;
lost was the glory, lost the power and kingdom.
2
3
Call on the hills to hide us
lest, men said in the City, the lord of charity
ride in the starlight, sole flash of the Emperor’s glory.
III
Evil and good were twins
once in the alleys of Ispahan; the Moslem
crying Alla il Alla destroyed the dualism of Persia.
Caucasia fell to the Moslem;
the mamelukes seized the ancient cornland of Empire.
Union is breached; the imams stand in Sophia.
Good is God, the muezzin
calls, but lost is the light on the hills of Caucasia,
glory of the Emperor, glory of substantial being."
https://theoddestinkling.wordpress.com/2016/05/12/an-introduction-to-taliessin-through-logres/