'Gernikako Arbola', the Basque name for the tree, is an icon of Basque culture. Ancient lords swore to respect Basque liberty beneath its branches and the President of the Basque Government, known as the 'lehendakaria', swears his or her fealty there.
The original tree in the Basque town of Gernika lasted for 450 years. Its first replacement, known as the 'old tree', stood from 1742 until 1892 and its trunk is still preserved in a nearby garden.
The second replacement was also hardy, surviving a Spanish Civil War aerial bombardment in 1937, made famous by Picasso's painting, 'Guernica' (the town's name in Castillian Spanish).
When General Franco's troops invaded the area, volunteers put an armed guard around the tree to protect it. The tree outlived Franco but died of a fungal infection in 2004.
Planted in 2005, the current tree is a direct descendant, grown from an acorn of its predecessor, but it has proven to be less enduring.
Experts have admitted defeat after experimenting with new drainage systems, fertilizers, oxygen injections and ditches to break up the compact soil of the site.
Local daily El Correo reported that its replacement, a genetic sibling, will be a 14-year-old specimen that began life in a nearby nursery before being moved to a local forest.
It is scheduled to be replanted in Gernika in February.