His death is best described by Tacitus :
"Arminius began to aim at a kingship, and found himself in conflict with the independent temper of his countrymen. He was attacked by arms, and while defending himself with chequered results, fell by the treachery of his relatives".
Arminius found out just before the Battle of the Weser River, from his brother Flavus, who was still fighting for the Romans, that both his wife and child were being well treated. It is believed that the boy Thumelicus was trained as a gladiator and was killed in the arena at a very young age. Some speculate as young as 15 or 16. Tacitus promises us in his "Annals" that he will tell of the fate of Thusnelda and Thumelicus, but their are gaps in this written history which probably contained that information that has been lost forever.
In life Arminius was a revered leader by his own people, and a feared enemy by his foes. Augustus was said to have mourned for months about his lost legions, and his heirs tried, but failed, to make the Germanic peoples pay for it. In death Arminius became a legend, easily on the same level as Beowulf, Sigurd, Hrolf Kraki, and even King Arthur, in my opinion. The one major difference is that we know for absolutely sure that Arminius existed and was a real person, and that his deeds were real, and far reaching. Never again would the great Roman Empire make any major attempts to subdue the Germanic peoples. The Rhine River becoming the furthest boundary of the Roman Empire's expansion. All of those of Germanic descent owe this great warrior a debt of gratitude for his daring ambush, and annihilation of 3 Roman legions, in the Teutoberg Forest on that fateful day in September of 9 C. E. If not this article might be written in Latin !
Germania - Tacitus
The Annals - Tacitus
The Roman Empire and its Germanic Peoples - Wolfram
The Battle That Stopped Rome - Peter S. Wells
The Roman History : From Romulus and the Foundation to the Reign of the Emperor Tiberius - Velleius Paterculus ( Ed. by Yardley and Barrett )
The Skillful Warrior of Old
The enemy's vanguard
From linking with his rear,
Large and small divisions
From working together,
From helping poor troops,
Officers and men
From supporting one another.
Act in concert.
Sun - tzu : The Art of War
Go with Odin's wisdom, Freyja's love, and Thor's protection !