It will be no good saying "don't mention the war" tomorrow when Spain and the Netherlands contest the World Cup final. The Dutch national anthem - sung, luckily, in a language few Spaniards understand - is all about war with Spain.
We often hear the commentators repeat their astonishment that Spain and the Netherlands have never been matched before in a major soccer tournament. The nations have, however, a long and distant history of bloodier conflict. The rest of the world is largely unaware of it. But if Germany had beaten Spain, and got to the final, the Dutch would face relatively trivial rivals. War against Spain moulded the Netherlands, created the nation, launched the Dutch Golden Age, and left an enduring legacy in the cultures of both countries. Before the game begins, the national anthem - a modified version of an anti-Spanish propaganda piece of the 16th century - will already have reminded the Dutch that their real historic enemy is Spain. There is no time for more than truncated versions at sporting events; so Spaniards will be spared the unfortunate 10th verse, which goes:
And when the Spaniard harms thee
My homeland, sweet and good
The thought of it alarms me
And my noble heart spills blood.
Like all old enemies, Spain and the Netherlands have intertwined histories. The links began in the 15th century, when the Netherlands was part of the dominions of the Dukes of Burgundy, whose courtly style won admirers in Spain. "Flemish" art, as they called it, shaped Spanish imaginations. In Granada, in the funerary chapel of Ferdinand and Isabella, the monarchs who sent Columbus to the New World, the paintings from their own collection capture the qualities that appealed to Spanish patrons: the gem-like colour, the cunningly understated emotional intensity, the mystical enigmas, the realistic tears and blood.
The shared cultural world was the background of a common political destiny. In 1516, by a dynastic accident, a young Netherlandish prince, Charles of Ghent, inherited the thrones of Ferdinand and Isabella. He arrived in Spain as a foreigner, trailing alien advisers, evincing misunderstanding, provoking rebellion. But once the rebels were defeated, Charles, like so many migrants from the north to this day, succumbed to Spain's seductions. He found the rarest of royal assets - willing taxpayers - and an exploitable aristocracy in a land where service to the crown defined nobility. In the 1520s and 1530s Spain conquered bullion-rich empires in Mexico and Peru. Self-interest as well as sentiment hispanised Charles. He spoke Spanish, he said, "to God, and Dutch to my horse". When he returned to the Netherlands, he was a foreigner among his own people.
His son, Philip II, wanted all his realms to be like Spain - dependable, fiscally productive, compliant. Netherlanders received him with the same xenophobic anxieties as Spain had shown Charles. Canals and rivers split the country among 17 disparate provinces, each with its own institutions, laws, and tenacious aristocracies. Religion exacerbated the divisions. Trade had spread protestantism around the North Sea, where small but ambitious congregations of the intrusively godly took over towns, smashed churches, and tried to evangelise Catholics.
By paternal ancestry, Charles and Philip belonged to the Habsburg dynasty, whose sacred responsibility was to guard the Church's altars. Philip took the job seriously. He embedded his palace near Madrid, the Escorial, in a monastery, where his bedchamber overlooked the tabernacle. He formed the world's biggest collection of saints' relics to protect them from blasphemy. He refused to rule over heretics. In the late 1560s, Netherlandish nobles, disaffected with a king who would not leave them to run their own provinces, formed an alliance with religious dissenters, under William of Orange.
The 80 Years' War, as the Dutch call it, followed (from 1568-1648). It was partly a civil war - pitching Protestants against Catholics and rebels against loyalists - and partly a war of independence, in which Spanish armies, mixing patience and terror, struggled in an unfamiliar landscape of waterways, bogs and floods, to reconquer rebel territories.
The war ended in stalemate and partition. Seven northern provinces formed an independent state, which eventually became the Kingdom of the Netherlands. The rest of the country - the future Belgium - remained an autonomous part of the Habsburg empire.
In Spain and the Netherlands, artists recalled the war with mixed feelings. Vermeer was a Catholic stuck on the Protestant-ruled side of the new frontier. In his most enigmatic canvas, the artist presents his back to the onlooker, while a drab, disconsolate girl models the Muse of History. A poignant map of the formerly united Netherlands fills a wall. Nostalgically, a chandelier surmounted by the eagle-symbol of the Habsburgs crowns the composition.
Velzquez, meanwhile, painted an image of magnanimity in victory - a Spanish general comforting his defeated rival at the surrender of the rebel Dutch stronghold of Breda.
By the end of the 17th century, Juan Valdes Leal, the most dynamic and forceful painter of the Spanish baroque, recalled the war with mingled bitterness and resignation. In one of his greatest paintings, an engraving of a triumphal arch, built to commemorate one of Spain's greatest victories, lies discarded on the floor, symbolising the vanity and fragility of worldly achievements.
Now, the war looks like an episode of shared experience. Philip II never understood the Netherlands, but he admired it. Just as he wanted the Netherlands to be more like Spain, so he wanted Spain to be more like the Netherlands. Addicted to penance, he hung his bedroom with Hieronymus Bosch's visions of hell, and encouraged Spaniards to copy Netherlandish art. That is why the pitch of so many palace roofs and the strapwork of so many ornate facades in Spain echo the Netherlands to this day. Meanwhile, without Spanish patrons, Dutch painting would have been much impoverished. In imitation of Spain's empire, Dutch adventurers founded a world-wide seaborne domain of their own and accumulated the wealth that erected the grand houses on Amsterdam's Heerengracht. The Dutch national dish - a rather unappetising confection of over-boiled carrots and potatoes - commemorates the diet to which a Spanish siege reduced the citizens of Leiden in 1574. Dutch children know few Dutch poems - they are too busy learning perfect English - but one universally loved rhyme tells of Piet Heyn's victory over Spain in 1628, likening the cannonballs he tossed at Spanish ships to "little apples from Orange".
Conflict is a good starting point for friendship - as the heroes and heroines of romance know. Like other peoples of the European Union, Spaniards and Netherlanders can now look back on their great war with emotion recollected in tranquillity, and see that peoples fight over what they have in common - uneasily shared spaces and legacies, contested interests, related but rival visions. Tomorrow, Spanish havoc may again make Dutch hearts bleed, or "apples of Orange" may land in Spain's goal, but any recrudescence of violence is unlikely to be worse than a biting tackle by Holland's zealous defender, Mark van Bommel. The first verse of the Dutch anthem enshrines respect for the foe:
I am a Prince of Orange
Free and unafraid
And honour to the King of Spain
I have ever duly paid.
So there will be no need to mention the war - but, probably, no harm if you do.