The beginning and the end of Arveleg's reign were forged in battle and in war. He became King when his father Argeleb I went to war with the newly allied lands of Rhudaur and Angmar, and was slain. Arveleg made an alliance of his own, with the Men of Cardolan and the Elves of Lindon, and struck back at the eastern lands.
These two allied forces seem to have cancelled one another out. For more than fifty years, Arveleg was able to hold a defensive line stretching east from Weathertop, through which Angmar could not break. Rivendell did not fall behind this frontier, it seems, and suffered a siege at this time.
At last the balance broke: Angmar gathered its forces and breached the frontier. Crossing the River Hoarwell, its armies marched westward and surrounded Weathertop, destroying its Tower and sending the troops of Arthedain in retreat back to Fornost. Arveleg died in that assault, and his young son Araphor came to the throne.
Arveleg I ruled Arthedain for fifty-three years, and was succeeded by his son, Araphor.
The date of Arveleg's birth appears only in The History of Middle-earth volume XII, The Peoples of Middle-earth. It cannot therefore be considered completely reliable.
Ar- is a prefix denoting royalty, representing Arveleg's claim to the entirety of the old lands ruled by Arnor. The ending -veleg is less sure, but it is possibly a mutated form of beleg, 'great' or 'strong'. The fact that earlier drafts of the histories of Arthedain have this King named as Beleg lends some credence to this idea.