THE EPIPHANY came as I stood on the dancefloor of Mama Juana’s salsa club, wearing a tiny plastic sombrero and a stick-on badge which said “Kiss me, I’m Mexican”.

To be honest, I wasn’t fooling anyone. My skin is white in that unmistakably British way, with blotches of red where it has been exposed to sunshine or bright cloud. I have about as much Latino blood in me as Donald Rumsfeld. But then, none of the Americans around me looked very Hispanic either. Take my friend Jade, who can be described only as Chinese; or Victoria, whose forebears came over from Plymouth on the Mayflower. Then there’s my wife, Lucie, whose parents are Czech and Slovak.

Yet there we were, in a red and amber dining room in Studio City, chugging Corona, wolfing shrimp tacos and moving in time (or thereabouts) to a ten-piece mariachi band. Around us, the sweaty faces were half white, half brown.

So my epiphany was this: the Americans should stop worrying about the assimilation of Mexicans. The work is already done — but the other way around. The Americans, always on the lookout for an excuse to drink beer, grill meat and wear silly hats, have done much of the assimilation themselves.

The bilateral event we were celebrating at Mama Juana’s on Friday was a perfect example of this — and proof that Mexico and its northern neighbour are more than capable of putting aside their differences and remembering what they have in common.

But what occasion, I hear you ask, is so life-affirming, so universally themed, that it can make all the fuss over the documentation and exploitation of immigrants disappear? What could possibly bring together the flags of red, white and blue, and red, white and green?

The answer, of course, is the defeat of the French, at an obscure battle on “Cinco de Mayo” (or May 5), in 1862. Never mind that the battle marked only a brief victory in an otherwise catastrophic failure to defend the Mexican homeland — which had been recently liberated from Spain then halved in size by the Mexican-American War. All the Mexicans choose to remember is this: 144 years ago, General Ignacio Zaragoza got one over Emperor Napoleon III’s army, using only a poorly equipped militia and a herd of cattle, which was set off in a diversionary stampede.

From what I hear, Cinco de Mayo was never a particularly important holiday in Mexico. It is the Americans who have helped make it so, by adopting it in the same way they adopted corned beef and Guinness on St Patrick’s Day. And why not? Kicking the French out of Puebla reminds the Americans of, well, kicking the English out of Boston. And it helps them forget about that other national Mexican holiday, on September 13, when the Latinos remember the niños héroes who chose to die instead of surrendering to the American invaders.

If you think the memory of the Second World War creates awkwardness between Britain and Germany, by the way, imagine how much the Americans want to discuss the Mexican-American War, during which they convinced Mexico to accept $18,250,000 for California, Nevada, Utah and parts of Colorado, Arizona, New Mexico and Wyoming. Before that deal, it was the Mexicans who thought they had an immigration problem, what with all the Anglo-Saxons charging across their border.

For the sake of everyone, it makes more sense to focus on Cinco de Mayo. This year, in particular, the celebration served as a reminder that the US and Mexico have far more in common than the border-patrolling Minutemen, or other anti-immigrant zealots, would like anyone to believe.

Indeed, Hispanic Americans are fond of arguing that the defeat of Napoleon III’s men in 1862 stopped the French from supplying arms to the Confederate Army for another year, thus helping Abraham Lincoln to win the Civil War.

This might be a bit far-fetched, but the spirit of the argument should be embraced. In my mind, all the talk of Latino immigrants being vital to the US economy rather misses the point. The bottom line is this: how upset can you be about Mexicans coming to live in Los Angeles, where half the streets (not the mention the city itself) are named in Spanish, and where the residents are voluntarily swapping their Big Macs for Baja Fresh burritos? Assimilation is clearly not the problem. Which leaves only the paperwork.

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