The securing of key oil installations in the south of Iraq, after defeating enemy troops, has been hailed as a significant victory for British troops.
The operation started at night
Royal Marines of 40 Commando made the successful air assault on the strategically important al-Faw peninsula in south-eastern Iraq.
The BBC's Clive Myrie said the marines were attacked by Iraqi soldiers defending the oil sites, but the enemy soldiers eventually gave themselves up waving white flags.
The efforts of the British forces has enabled these oil fields to be preserved and avoided a potential ecological disaster, he said.
Combat units from the Royal Marines in conjunction with 60 US Navy Seal commandos were involved in the helicopter assault.
A 20-minute low-level helicopter flight beneath Iraqi radar made them targets for any enemy forces.
And the Marines faced resistance from the moment the first helicopters landed in the middle of the complex, from Iraqis concealed in bunkers and dug outs around the main oil stations.
"Iraqi troops opened fire and air support was called in by the Marines," said our correspondent.
He said the strength of enemy forces had been initially estimated at 1,300 soldiers and civil militiamen, with reports of reinforcements later.
Precision guided munitions were then dropped on the bunkers, while the marines themselves attacked with mortars.
Two smaller groups of marines and Navy Seals landed by oil pipe heads nine
kilometres further south by the coast, it was reported.
The forces at al-Faw were backed by massive firepower from the air, reportedly including two circling US AC-130 Spectre fixed-wing gunships and two A-10 Thunderbolt ground attack jets.
"By first light Iraqi soldiers were surrendering in their dozens, waving white flags and leaving their dug outs with their arms in the air," said our correspondent.
Troops are fanning across the peninsula
Dozens of Iraqi troops are believed to have surrendered as prisoners of war, with a number reported killed.
Throughout the night British forces had used enormous loudspeakers to urge the enemy to lay down their arms.
It is understood some kind of detention centre will be set up in the area to keep the prisoners of war.
Securing the oil infrastructure in this part of Iraq is highly significant, averting both an "immense ecological disaster" and preserving the oil wells for the rebuilding process after the war.
Group Captain Al Lockwood, at Central Command in Qatar, said marines were able to capture both oil heads in the Gulf and the pumping station.
"This is a concern for us because the regime could have polluted the gulf with oil," he said.
The al-Faw peninsula controls the straits up to the port, he said.
"The port itself is valuable to us because it's going to be our main focus
for bringing humanitarian aid to Iraq," he added.
Marines spent much of Friday fanning across the rest of the al-Faw peninsula, said our correspondent.
The operation was named Houghton after a veteran World War Two commander of 40 Commando, "Titch" Houghton.