Like militias espousing starkly different beliefs, forces from the opposite poles of the red wine world paraded into town at the end of last month. On one side were the Napa Valley Vintners with their “big” wines — deeply colored, ultra-ripe, assertively flavored, and high in alcohol. On the other side, the Union of Grand Crus of Bordeaux arrived with their “traditional” wines — less opaque in color than the big reds, not nearly so fruit-assertive, and lower in alcohol. You’d be hard put to guess that wines so divergent in impact could be based on the same grape: cabernet sauvignon.

Is one style of cabernet better than the other? Have the New World forces overwhelmed those of the Old World? Or do the traditionalists hold their hallowed ground in Bordeaux? I tasted numerous examples on both sides to find out. Happily, on this battle line, only red wine was spilt.

In the opening show of forces, at a lunch hosted by the Napa Valley Vintners at the University Club, a platoon of forceful young cabernet sauvignons seemed indomitable. These admittedly elite wines from Staglin Family Vineyards, La Jota, Tres Sabores, ZD, Silverado, and Robert Mondavi were each so opulent, warming, and potent in their dark-fruited flavors that the memory of traditional wines was effaced, at least as long as I was under their spell. Though not the most massive, my preferred “cabs” for current drinking were the Robert Mondavi “Oakville” 2002 ($45 at postwines.com) and the ZD Reserve 2002 ($120 at 67wine.com). Alcohol-wise, these two wines were the least heady of the group — but only relatively.

As anyone who checks the small print on “big wine” labels can’t fail to notice, alcohol levels are rising. California wines once fell into the same 12% to 14% category as traditional European wines. Now, they hover at 15% or higher. Winemakers will tell you that their aim is to maximize flavor ripeness, not alcohol, and so they let sugar levels continue to elevate even after the grapes are technically ripe in order to achieve more intense flavors. Higher sugar translates into heftier alcohol. When I once questioned a California winemaker about a chardonnay he’d made, which carried 16.2% alcohol and which was doing a slow burn at the back of my throat, he shrugged and said, “I can get ripeness in my Central Coast vineyard that Burgundians can only fantasize about.” He added, “Would you eat a peach before it’s fully ripe?”

No, I don’t want to eat an unripe peach, but neither do I want it to carry 16.2% alcohol. That monster chardonnay was unoaked, which probably emphasized the alcoholic wallop. To be sure, wines with big fruit, a dollop of spicy oak, and just the right acidity can hide their high alcohol content. I’ve been fooled by high octane fruit bombs from South Africa and Australia, as well as from California. While big wines can fool the palate, they can’t fool your brain. You’ll feel them quicker than you will a less potent example from the Old World.

Of the dozens of Bordeaux winemakers who shared the town with Napa folks last month, Marcel Ducasse of Château Lagrange in St. Julien has never made wines that could be described as his region’s most powerful. The heavy artillery of Bordeaux, such as Latour and Mouton-Rothschild, lie further up the Medoc peninsula in the commune of Pauillac. While Lagrange lacks big muscles, it does exemplify the Bordeaux touch points of equilibrium, finesse, and reticent flavors that bloom rewardingly, given time in the bottle and attention in the glass.

Ironically, Lagrange, the largest Medoc chateau at 388 acres, had fallen into disrepair and poor winemaking practices until the Japanese firm Suntory, which purchased the property in 1983 for $10.8 million and sunk $40 million more into improvements, rescued it. It took years for the wines to begin to reap the rewards of the new regime’s hard work in the vineyards and winery. Over the last week, I’ve tasted half a dozen vintages of Lagrange. Smart collectors looking for performance in the glass rather than on the label have caught on to this property’s rising star. The 2002 Lagrange ($37 at Rochambeauwines.com) is the clear choice to buy now. It’s a brilliant wine, melding red currants and a whiff of tobacco smoke, with unexpected ripeness and readiness in this unglamorous vintage.

The one sure way to dim the star of a beautiful Bordeaux like Lagrange 2002 is to drink it after a Napa Valley cabernet. It will get steamrolled by greater volumes of ripe fruit flavor, alcohol, and just plain muscularity that are New World signatures. To come back to the opening question: Is one style better than the other? I’d hate to do without either the big wines of Napa (especially with a charbroiled steak) or the traditional wines of Bordeaux. Yet I recall a Frenchman once telling me that, when you’re dining with a lover or friends, it’s the last glass of a bottle of wine that should taste the best, not the first. On that basis, the nod goes to Bordeaux.