With fresh arms and a renewed vigor from an increasingly intense NATO bombing campaign, anti-government rebels in Libya have made tangible gains over the past few days. The rebels captured the airport in Misurata, and sent Gadhafi loyalists fleeing for cover. The airport served as a base and storage facility for Gadhafi’s forces and their heavy weapons. Rebels say they’ve seized weapons and ammunition from the airport. Rebels are now advancing west from Misurata to Ziltan, which is closer to Tripoli. Fighting has subsided on the eastern front around Ajdabiya as well. Gadhafi has gone underground, not even appearing at his son’s funeral, which has fed the rumor mill.

The rebels have not proven themselves totally skilled at holding territory once they capture it, so we’ll have to wait and see on that. But I’m not sure we can say that the military operation has prevented a massacre anymore. First of all, there have been plenty of deaths, including those springing from the intensified attacks inside the war zone.

Hundreds — possibly thousands — of African migrants have drowned or disappeared at sea trying to flee Libya for Europe in overcrowded boats that are not seaworthy, reports from refugee agencies suggest.

Hundreds of people are missing after the ship Abdi was on went down last Friday, while 250 people died in a shipwreck at the beginning of April, and two boats with 480 people between them have simply vanished, the United Nations High Commissioner for Refugees said.

UNCHR is “actively discouraging” migrants from boarding boats for Europe, Melissa Fleming, a spokeswoman for the agency, said Tuesday.

The boat migration, I would argue, comes directly from the instability of a civil war, and the bombing campaign certainly adds to that. This is not to say NATO somehow caused hundreds of deaths from boats capsizing, merely that this kind of occurrence is depressingly normal during a time of war.

Far more troubling is the rough justice being pursued back in Benghazi, in so-called “Free Libya.”

Three weeks ago, a traveler spotted a man’s body in the farmland on this city’s outskirts, shot twice in the head with his hands and feet bound. He had disappeared earlier that day, after visiting a market.

Ten days later, near the same spot, a shepherd stumbled upon the body of a second man, killed with a single bullet to the forehead. Masked, armed men had taken him from his home the night before, without giving a reason, his wife said.

The dead men, Nasser al-Sirmany and Hussein Ghaith, had both worked as interrogators for Col. Muammar el-Qaddafi’s internal security services, known for their brutality against domestic dissidents. The killings, still unsolved, appeared to be rooted in revenge, the families said, and have raised the specter of a death squad stalking former Qaddafi officials in Benghazi, the opposition stronghold.

The killings have unsettled an already paranoid city, where rebel authorities have spent weeks trying to round up people suspected of being Qaddafi loyalists — members of a fifth column who they say are trying to overthrow the rebels. If the violence continues, it will pose a stern challenge to a movement trying to present a vision of a new country committed to the rule of law, while potentially undermining hopes for a peaceful transition if Colonel Qaddafi surrenders power.

The Libyan uprising started like the other peaceful uprisings in the Arab world, but then immediately turned violent. That is facilitated by Gadhafi’s use of mortars and heavy weapons, of course, but we’ve seen that elsewhere. What we haven’t seen is revenge killings on a mass scale by the protesters and democratizers. It suggests that a post-Gadhafi landscape in Libya could look just as violent as before. To quote Matt Yglesias:

The sad reality is that the existence of a bona fide bad guy doesn’t magically call a team of equal and opposite good guys into existence. On the contrary, once a political conflict becomes a contest of violence versus violence you’re all but destined to be looking at a nasty situation. Inserting ourselves into these kind of conflicts just isn’t the most promising outlet for humanitarian impulses.

The hope is that Libyans can find a principled leader to preach nonviolence and the importance of civil society and allow Libyans to aspire to a better life. But I don’t see why we should put much faith in that hope. And so this “humanitarian” intervention appears to have come in on the side of a group that isn’t entirely humanitarian in their actions.

UPDATE: By the way, if you thought that Congress might actually poke their head out and ask for the authority of war powers again with a resolution approving the intervention in Libya, think again.