Drinking. Brawling. Hurting.

The wounds on my friend Pete Yazgier's head come in as many colors as Cezanne's fruit bowls.

Cherry-hued flecks dot the left half of his skull -- grim mementos of the rocket-propelled grenade that walloped his armored vehicle in Baghdad last September. A bright scar bends like a stalk of rhubarb above his left ear, the result of six surgeries to treat the brain cancer doctors found while ministering to his shrapnel wounds; they fear the tumor was caused by depleted uranium that Pete, 28, handled as an Army mechanic.

And now, a plum-like bulge on his upper right jaw ripens before my eyes. This, oddly enough, is the one that really scares me: It's the aftermath of a Marine's clenched fist that hurled into Pete's face just moments ago.

Only the bar gods know exactly how the skirmish began. But I'm guessing it went something like it did just the week before:

Marine: "Hey, [fornicator], what are you staring at?"

Army guy: "I don't know, you [fornicating] Jarhead, you tell me."

Marine: "I think I'm staring at a [fornication-head] who's about to get his [buttocks] kicked."

Lame invectives turn to blows. Soused onlookers hustle to their buddies' defense. Only when a huge bouncer enters the fray do flying fists cease and desist -- Marines head for the front exit, Army guys to the bar. As I search for ice to press against Pete's busted cheek, the cops appear, looking downright bored by the redundancy of the mayhem.

Yes, sir, it's another Friday night at R.J. Bentley's Filling Station, a cozy bar in College Park, where wounded Iraq and Afghanistan veterans being treated at Walter Reed Army Medical Center come to fuel up on Coronas, honky-tonk dance and the "Rocky"-style pummelings I've seen on half a dozen visits this summer.

Venture here around dinnertime, and you'll find University of Maryland professors eating fettuccine with their kids. But stay until the floors start getting sticky -- say, around 11 p.m. -- and it's a different world altogether: a chance to brush up against college football hunks and thin girls in slinky tube tops, and also, perhaps, to witness some of the raw consequences of two faraway wars brought home.

Half a decade into the "war on terror," America's bars have become our barometers: instruments that measure the extent to which our veterans have been left to wrestle alone with substance abuse, anxiety disorders and other mental health problems after long tours in Iraq and Afghanistan.

The men and women who come back from the traumas of war "are often hyper-alert, quick to respond and susceptible to a loss of impulse control," says clinical psychologist Jeffrey Jay of the Center for Post-Traumatic Stress Studies in Washington. "The brain is actually altered by these experiences -- it's part of a survival mechanism, and it's very confusing for them."