It’s the late 1300s. The Castilian Civil War just ended and families in the Basque Country are jockeying for political power in the vacuum left behind. Old feuds that have simmered for centuries ignite. Families build towers to fortify their lands and their surroundings. The aide (or ahaide) nagusiak, the leading kinsmen, gather strength. War erupts between two families and their associated allies. This is the War of the Bands.

• The war began as a series of street fights, first in Bilbao in 1362 and later in the markets of Bermeo in 1413, between the Legizamon and Zurbarán families. Other actors joined in and fighting continued in earnest until at least 1433. Other families fought each other, including an alliance of the Gamboas, the Alzates, and the Baldas in Gipzkuoa who fought Juan de Saint Pedro and his allies the Oñaz and the Lezcano. As men died and fortresses burned on both sides, new feuds developed.
• The main source we have about the War of the Bands comes from one Lope García de Salazar and his Las Bienandanças e fortunas — Book of Luck and Happy Chances. Written near the end of his life, this 25-volume work traces the history of the world, from the creation through Israel, Greece and Rome, to Spain, and ultimately to the events of his own life. He played a large role in the War of the Bands and his accounts are one of our best sources for medieval Basque history.
• The war, or maybe more properly blood feuds, was an attempt by the aide nagusiak, the leading kinsmen or elder relatives, to exert that status to consolidate power and form a local nobility. By leveraging ties of kinship through land and its production, these elders tried to create their own fiefdoms, but were only moderately successful, becoming, at best, “lords without lordships,” or lords without formal titles.
• While the Wars started out as inter-family fighting, as the self-proclaimed lords tried to exert power over surrounding towns, it seems to have evolved into a rural-vs-urban conflict. As these lords tried to control their neighboring towns, those towns, which had a very different view of social order and commercial development, pushed back. This ultimately led to the governing boards, or juntas generals, gaining authority within the cities.
• It can be argued (as it is by José Ángel Achón Insausti) that, through this process of first men exerting power and then cities responding by establishing their own authority, the Basque concepts of universal nobility and self-government that are central to the fueros came to be.

Primary sources: Wikipedia; Achón Insausti, José Ángel; Las Guerras de Bandos. Enciclopedia Auñamendi, 2020. Available at: http://aunamendi.eusko-ikaskuntza.eus/es/las-guerras-de-bandos/ar-153913/