When Does "Arak: Son of Thunder" #1 (1981) Take Place?
"ARAK: SON OF THUNDER" #1 "The Sword and the Serpent!" is a fantasy historical fiction comic-book written by Roy Thomas that released May 12th, 1981. So when is "Arak: Son of Thunder" #1 set?
It takes place on the fictional DC Comics Universe timeline in the year:
We know this because during their wintertime stay Hermold the Frank says, ..."in the Frankish kingdom, ruled by King Charles, whose Latin name is Carolus Magnus." and Arak replies, "Ah, yes... I've heard you speak of the Frankish king from time to time." and, then, "Perhaps one day we'll sail far enough to meet him." The real-world French King Charlemagne (748-814) was also known in different regions as Charles, Karl der Große, Karel de Grote, as well as Carolus or Karolus. Therefore he is the living ruler who reigned from October 9th, 768 AD to his death on January 28th, 814 AD Hermold is referring to so it must be sometime during or after October of 768 AD and before or during January of 814 AD.

793 AD - 794 AD
We know this because during their wintertime stay Hermold the Frank says, ..."in the Frankish kingdom, ruled by King Charles, whose Latin name is Carolus Magnus." and Arak replies, "Ah, yes... I've heard you speak of the Frankish king from time to time." and, then, "Perhaps one day we'll sail far enough to meet him." The real-world French King Charlemagne (748-814) was also known in different regions as Charles, Karl der Große, Karel de Grote, as well as Carolus or Karolus. Therefore he is the living ruler who reigned from October 9th, 768 AD to his death on January 28th, 814 AD Hermold is referring to so it must be sometime during or after October of 768 AD and before or during January of 814 AD.
Specifically, the main action depicts two attacks on a monastery and in the next issue, "Arak: Son of Thunder" #2 (1981), Lord Hessa says, "Silence, viking! I know how your kind treated the monks at Lindisfarne and Jarrow, these past summers"... The tragic real-world Viking raid of the monastery on Lindisfarne island happened on June 8th, 793 AD so it's June of 793 AD.
Later, halfway through the issue the unnamed narrator tells us, "When the shroud of winter drapes the land of the vikings"... and, then soon after, "Spring comes... season of life." So we pass from the winter of 793 AD to the spring of 794 AD.
Immediately afterward, we see the second tragic real-world Viking raid on the double abbey house known as Monkwearmouth–Jarrow, which happened in 794 AD. Again, in the next issue Lord Hessa says, ..."the monks at Lindisfarne and Jarrow, these past summers" so it's the summer of 794 AD at the end of the issue.
Additionally, the comic opens with a prologue that gives us Arak's origin story and as it ends the main action in 793 AD begins with a relative time setting textbox that reads: "Another misty morn... eight years later!" So presumably it is 785 AD when Arak is found adrift on the Atlantic Ocean by vikings.
793 - 8 = 785.

