In 723 an Anglo-Saxon missionary stood axe in hand before the holiest tree of the Hessians – the oak sacred to the thunder-god Donar near Geismar. He struck. And the expected lightning never came. That single scene became a turning point in the Christianisation of central Europe.
The tree was sacred to Donar – the Germanic thunder-god we know from the North as Thor. A mighty, ancient oak near Geismar (today part of Fritzlar in northern Hesse) was holy to the people. That is exactly why it was chosen: whoever fells a god’s tree and goes unpunished, so the reasoning went, proves that his own god is the stronger.
Sacred trees and groves were at the heart of Germanic religion – no temple of stone, but living nature. In many places the oak was the tree of the thunder-god: it draws the lightning, defies storms, grows ancient. A Donar oak was the guardian and power-place of a whole landscape. To touch it was unthinkable – and therefore the perfect stage for an example.
Boniface (really Wynfrith, an Anglo-Saxon monk) did not act alone: behind him stood Frankish power, with a base on the Büraburg near Fritzlar. Before an audience – surely planned and announced – he had the oak felled. From its wood a chapel dedicated to St Peter was built on the very spot: the old sanctuary was literally turned into the new one.
The heart of the story is the lightning that never struck. Donar took no revenge, the oak fell, and nothing happened to the missionary. For the onlookers this was proof of God – many were baptised. It was a propaganda victory foretold, cleverly staged at a place charged with meaning.
Striking as the image is, it rests on a single source: the Vita Bonifatii of Willibald (c. 760), a saint’s life written to glorify Boniface. Willibald even reports that a sudden gust from above split the tree – a pious miracle motif. Place, sequence and detail are therefore coloured by the source’s intent; what the oak really looked like, or exactly where it stood, we do not securely know.
Thor / Donar · Thor’s Hammer · The Externsteine.
Willibald, Vita Bonifatii auctore Willibaldo (c. 760). Scholarship: Lutz von Padberg, Bonifatius (2003); Rudolf Simek, Dictionary of Northern Mythology. On place-names: Wodan/Godan in Gudensberg & Bad Godesberg.