The first sign of trouble comes early.
A huge mushroom cloud shoots into the air. A car bomb has just detonated, killing four Iraqi soldiers and wounding eight more.
A Humvee carrying soldiers from the U.S. Army's 3rd Armored Cavalry Regiment is careening through the pitted streets of western Mosul, dashing through side roads and pushing its way through traffic to avoid the ever-present dangers of roadside bombs — or IEDs, as the military calls them.
The northern Iraqi city is the scene of some of the fiercest fighting in the country now. Iraqi Prime Minister Nouri al-Maliki has said Mosul is where al-Qaida in Iraq is making its last stand. U.S. commanders don't see it that way, but there is no doubting the heavy insurgent presence in the city.
On this day, the soldiers from the 3rd Platoon, 3rd Squadron of the regiment are tense — with good reason. The second sign of trouble doesn't take long to appear.
The convoy enters a crowded neighborhood with houses close on both sides. The street is suddenly empty.
Then, the convoy takes fire from all sides.
Staff Sgt. Jimmy Whetsone says they were expecting something like this.
"I believe that al-Qaida has moved out into that neighborhood," he says. "We got briefed this morning that down in the south neighborhood right there, they're starting to collect."
Working to Secure a City at War
American soldiers come under attack on almost every patrol. The city's buildings are pitted with bullet holes. There are collapsed bridges — the result of car bombs. Graffiti supporting the insurgency tattoos many walls.
While security has improved in many parts of Iraq, Mosul is at war.
Intelligence officers say there is an al-Qaida presence in the city, including foreign fighters, but there are also a number of other insurgent groups — like Ansar al-Sunna, Jaish al-Islam and the 1920s Revolution Brigades, to name a few.
The U.S. military stresses that there is going to be no massive U.S. troop surge like in Baghdad, nor will they launch a full-scale offensive like they did twice in Fallujah. And they won't be using local Sunni tribal paramilitaries or what they call concerned local citizens, or CLCs, like in Anbar province and elsewhere.
"No single tribe wields that kind of power in Mosul," says Maj. John Oliver, the operations officer for the 3rd Squadron, 3rd Armored Cavalry Regiment. "The city is too fractured, too disparate, for any one group of people to really wield that much authority."
Oliver says Mosul is a fairly well-integrated multi-ethnic city with Christians, Shia, Yazidis, Kurds and Sunni Arabs.
"So all we would get if we tried to arm CLCs ... in Mosul is you'd empower one group versus another, and you'd probably make the problem worse rather than better," he says.
Instead, commanders say, the 1,400 U.S. soldiers in the city are being bolstered by 9,000 Iraqi army troops, many of them Kurds, who are expected to do most of the work of securing the city.
A Final Showdown?
Members of the 4th Platoon try to learn a few Kurdish words over lunch at a command outpost by the Tigris River in the western part of Mosul.
The plan is to set up these small outposts — basically mini-garrisons — all over the city, housing both U.S. soldiers and the Iraqi army.
At this outpost, which has been operational for about 10 days, U.S. forces and Iraqi troops are supposed to do their first joint patrol, but the Iraqis complain about being under-equipped for the mission. Instead, the U.S. force heads out alone.
A strictly enforced curfew leaves the city deserted by nightfall, except for insurgents who use the dark to plant IEDs and the U.S. patrols that hunt them.
In the darkness, Sgt. Barret Taylor spots a dead dog in the road.
"It's one of the tactics that they use," Taylor says. "They'll stuff a bomb inside a dead carcass and throw it out in the middle of the road and just wait for somebody to assume it's just a dead animal and drive up on it."
It turns out to be nothing.
That Sunday, though, U.S. forces were hit with eight IEDs, eight rocket-propelled grenade and shooting attacks and the car bombing.
It was considered a light day.
Al-Maliki called Mosul the last stronghold of al-Qaida and said there would be a final showdown in this city. Still, U.S. military commanders say that is not the way the fight in Mosul is going to play out.
"Our enemy here is not going to do some kind of final stand where they die to the last man," Oliver says. "The only time they die to the last man is when you have them cornered. Otherwise, they will shoot at us, they'll engage us, they'll conduct attacks and then they'll vanish like vapors in the wind. And there's no doubt in my mind that they'll do the same thing here in Mosul."