They were first U.S. troops ever to set foot in this Taliban stronghold, reports CBS News chief foreign correspondent Lara Logan.
"We're on the offensive now instead of the defensive," said Lance Corporal Andrew Zemore. "It's good to get out here on the offensive."
The Taliban had no intention of giving up this strategic base easily - intense fighting went on for eight hours.
Taliban gunmen firing back from hidden positions on rooftops and courtyards. Their resistance was so strong, the Marines say the militants must have known they were coming.
Ramming their truck through a wall, Marines broke into a suspected Taliban compound looking for drugs and weapons. They seized 66 pounds of opium, not surprising in this town. Dehaneh is vital to the Taliban's drug-running operations here in Helmand province.
"By liberating Dahaneh we free the local populace from the influence of the Taliban," said Capt. Zachary Martin, commander of Golf Company, 2nd Battalion, 3rd Marines. "They are able to go about their daily lives without being faced with intimidation or murder."
And, the Marines are hoping, be able to vote in next week's presidential election. That's what this operation is really about.
The Taliban has vowed to disrupt the elections and across Afghanistan, attacks are on the rise. The United States knows that if the Taliban is able to stop large numbers of people voting in the South, the credibility of the election could be in doubt. That makes operations like Wednesday's especially critical, but there is only one week left before Afghans go to the polls.