The Thunder Tree 

Known in England, as Monarchs of the Forest and venerated throughout Europe for their strength, durability, and hardness, oak trees were traditionally planted on the boundaries of lands. The survival of this custom is evident in the so-called Gospel Oaks of many English parishes. 

In the mythological beliefs of many ancient cultures, the oak was the first tree to be created and humans sprang from it. In antiquity, the oak was sacred to the Hebrew people because Abraham reputedly received Jehovah’s angel under its branches. The ancient Greeks dedicated the oak to Zeus because his Oracle in Dodona was located in a grove of oaks. Here, all oracles were delivered from the tops of the oak trees, priests interpreting the rustling of the oak leaves in the wind as the voice of Zeus. The Romans consecrated the oak to Jupiter because it had sheltered him at his birth, and originally, the image of Jupiter was represented solely by a natural oak tree. 

To the Celtic priesthood known as the Druids, found in Britain, France, and Ireland, the oak represented the Celestial Tree and was considered a principal object of worship. All Druidic ceremonies reputedly included the oak and its parasite, the mistletoe. The Druids worshipped in holy oak groves, their midsummer festival characterised by the gathering of the sacred mistletoe from oak trees, and solely, the friction of oak wood kindled the midsummer need-fires. Pliny the Elder erroneously derived the name Druid from the Greek term drus, meaning ‘oak’. He did not know, however, that the Celtic word for oak was very similar, namely daur. Therefore, druid was a Celtic word describing the ‘priest of the oak’. The oak was also the sacred tree of the pagan deity Dagda, the creator of the ancient Irish Gaels, whereas the Germanic tribes similarly ranked the oak first among their holy trees.

The cult of the oak tree became universal throughout Europe in prehistoric times. It was observed that the oak tree was struck by lightning far more frequently than any other tree. Therefore, it was widely deduced that the oak must surely be the dwelling place of the god of thunder. In Scandinavia, the oak was sacred to Thor, the god of thunder, and further south, to Donar, his Teutonic counterpart. For this reason, the oak was known as the ‘thunder tree’ and a Sussex rhyme intones: ‘Beware the oak; it draws the stroke’. However, in time, the incorrect lore developed that the oak ensured safety from lightning strikes, and around Europe, oak branches were traditionally kept in houses in the belief that this protected against lightning.

As sacred to Thor, the oak was seen to be under his immediate protection. Hence, it was considered sacrilege to mutilate this tree in any way, and with Thor’s tree standing in every hamlet, it must have provided a great sense of security to all. An unwritten law among Germanic and Celtic tribes was that oak trees were not to be felled, and that bad luck would follow anyone who chopped down such a tree. It was this very belief that the Anglo-Saxon missionary Boniface (circa 680–754) tapped into when he used the sacred status of the oak tree amongst Germanic tribes to win thousands of converts to Christianity. He accomplished this by publicly chopping down Donar’s Oak – known as Thor’s Oak in Scandinavian countries. By this act, he assured all people watching that their god, believed to be residing in the sacred tree, did not have the power to avenge the destruction of his abode and that the Christian God was the far more powerful – his ploy was convincing, as it earned him the title ‘Apostle of the Germans’.

Oaks and their leaves were also believed to have powerful protective powers against witchcraft and magic. The Venerable Bede (circa 673–735), Anglo-Saxon scholar and historian, recorded how the heathen King Ethelbert forced the proselytising St. Augustine – sent by Pope Gregory I to convert the Anglo-Saxons to Christianity – to preach to him under an oak tree rather than indoors. This was done so that the sacred oak could protect the fearful Ethelbert from any spell the unfamiliar Christian missionary might cast on him. 

The choice of oak-leaf clusters as a military decoration hails back to the ancient Romans. According to Pliny the Elder, a wreath of oak leaves, called the Civic Crown, was given to any Roman who saved a fellow citizen in battle.²²⁶ Similarly, soldiers who had performed feats of bravery or selflessness were honoured with the presentation of an oak-leaf crown. After battle, it was customary for Roman soldiers to place wreaths of oak and myrtle on their swords, and the ancient Greeks awarded a crown of oak leaves to the victors at the Pythian Games, held in honour of Apollo – next in importance to the Olympic Games in Greece.

The oak’s qualities of endurance and resilience made the timber from these trees ideal for shipbuilding, and records show that, on average, about 3,500 full-grown oak trees were used in the construction of a three-decker battleship.²²⁷