By Paul Wood
BBC News, embedded with the US marines
After a day of taking continuous sniper fire, the marines decided to call in air strikes.
The marines' new base has become an easy target for insurgents
Four or five huge bombs were dropped on buildings right on the perimeter of their base - on places where their attackers were hiding out.
The sniping continued. So Alpha Company began to push out into the city on foot, to find the insurgents.
It was a simple tactic.
Insert the grunts, as the ordinary marines refer to themselves, into an area. Wait until they draw fire. Then kill the enemy which has just revealed itself.
I followed the foot patrols in an armoured column.
It was not long before the marines were taking small arms and rocket-propelled grenade fire.
Half a dozen marines stood up through the open roof of their vehicle, amazingly calm, almost unflinching as grenades fizzed overhead.
Then they opened fire. Thousands of rounds of automatic weapons fire, with tanks aiming shells in support.
The marines moved through Falluja block by block.
The gun battles had been raging for two hours continuously when their vehicle was sent back to base with wounded - two men yelling in pain from shrapnel injuries.
They both survived, although their M16 automatic rifles lying in the bottom of the vehicle was sticky all over with blood.
Fighting is continuing around the marine base through the hours of darkness.
One marine officer acknowledged to me that the insurgents had been able to regroup.
But he said it was a sign of their weakness that they were only able to carry out sniper attacks or hit and run grenade attacks, rather than assault the marines frontally.