MOSUL, Iraq - The Islamic State militants slipped into their boats and crossed the Tigris under the cover of heavy skies, fanning out on the eastern bank near a ramshackle fairground known as the "Mosul Jungle", and prepared their assault.

But Iraqi forces were waiting.

"Fourteen fighters crossed the river, followed by a second boat of fighters," a commander from Iraq's elite Golden Division told Middle East Eye. "There was strong fighting, but they were trapped and couldn’t get back across so we killed them all."

Golden Division forces then called in an air strike on the second boat, ending the threat in an eruption of water and flying wreckage.

They are using rowing boats, boats with engines and they are now even swimming across the Tigris - Captain Mohammed, Golden Division

It was the first of two amphibious assaults by IS in recent days in the city, with fighters crossing from the IS-controlled west of the city to harass the forward positions of Iraqi forces on the east.

They have been aided by poor weather and clouds, preventing aerial surveillance, but the keen eyes of Iraqi soldiers have thwarted their attempts.

Undeterred, four militants tried the same tactics the next day. Again, with fatal consequences.

"They are using row boats, boats with engines and they are now even swimming across the Tigris and then hiding in the trees," said Captain Mohammed from the Golden Division. "They will use anything and everything to try and breach our front lines along the river."

The captain said IS militants who managed to reach eastern Mosul focused their attacks on riverside positions held by the regular Iraqi army, deemed weaker than the Golden Division, which has steadily handed over its forward positions that now run the length of the eastern side of the Tigris.

"They are scared of us, we found out they call us the 'Black Killers’ because we always dress in black," he said.

Golden Division troops prepare their rooftop position overlooking the 'Mosul Jungle' (MEE Tom Westcott)

"Maybe some of them do really believe that they can take back control of east Mosul, but for most of them, I think it’s enough to just to try and kill some of us. They want to die fighting because they believe they will go to paradise."

Full-spectrum assault

Further attacks from the river are expected and following the recent IS breaches, some special forces soldiers have had leave postponed to continue supporting the front lines.

But IS has also been trying to weaken army positions with a relentless bombardment of mortars, drone-borne explosives and sniper attacks.

Newly arrived reinforcements from the regular army enthusiastically piled out of Humvees near a central frontline position on Sunday.

One carried a small cage of pigeons, saying it was an Iraqi tradition to release the birds for good luck. Within a few minutes, the whiz of incoming sniper fire sent them scattering for shelter.

They quickly unloaded the Humvees, bent low trying to keep out of sniper sight as they carried heavy ammunition boxes, backpacks and blankets.

"This is the first time we’ve had IS snipers targeting these positions," said Golden Division officer Hassan. "We suspect one of the local residents around here gave them information about our positions."

Iraqi army troops arrive with 'lucky pigeons', and immediately come under fire (MEE/Tom Westcott)

From mosques in western Mosul, the call to prayer echoed out across the river.

They made announcements saying, 'Allah is on our side not on yours'... we laugh because God is for everyone, not just them - Hassan, Golden Division officer

"When the wind is blowing towards us, like today, we can hear everything from western Mosul really clearly and Daesh know we can hear them," said Hassan.

"Yesterday they were singing 'Takbir' all day," he said in reference to a call often played on repeat during times of war.

"They made announcements from the minaret loudspeakers saying, 'Allah is on our side not on yours', but we just laugh at this because God is for everyone - not just for them."

As the muezzin’s call faded, from a nearby rooftop Golden Division gunners rattled fire upon IS-held western Mosul.

Downstairs, the radio crackled with an alert that an IS armed drone was circling overhead.

One of the Golden Division officers radioed nearby positions instructing forces to ensure all vehicles were under cover.

Many of the army's Humvees, made in Egypt, are of low quality and easy pickings for IS drone bombs.

A volley of gunfire overhead indicated that the soldiers on the roof had spotted the drone but, small and high-flying, even the most experienced gunners find them difficult to shoot down.

"Daesh are now using a lot of armed drones. The images are relayed back to some IS fighter with an iPad over in western Mosul and, if he sees a Golden Division Humvee on his screen, that will be his principle target," said Captain Mohammed.

"But they are also injuring a lot of civilians and children with these attacks."

On Tuesday, IS drones reached as far into eastern Mosul as ‘Jonah’s Tomb’, liberated a fortnight ago, injuring six Iraqi workers on a tea break while repairing damaged infrastructure.

Puddles of blood from the wounded men and smashed tea glasses still covered the ground. The bomb fell two metres from the group.

Jonah's Tomb, a historic hilltop shrine sacred to Muslim and Christians alike, was demolished by IS after they seized control of Mosul in 2014.

Golden Division 2nd lieutenant Amar prepares to fire at IS positions (MEE/Tom Westcott)

Since its liberation, hundreds of Mosul residents and Iraqi armed forces have flocked to what remains of the shrine to pay their respects.

A temporary mobile phone mast, powered by a big generator, was erected there to supply service to areas of the city that IS long kept without network coverage, which may have been the intended target.

Divided by war

Unperturbed by the daily threat of these drone-borne missiles or stray IS mortars, eastern Mosul is thriving. Shops have reopened for business and fruit-laden stalls line streets where bulldozers clear away debris of air strikes and fighting.

This war-battered half of the city stands as a paradise to desperate residents of western Mosul who are still trying to flee from IS and the fighting that is expected to start there in the next few weeks.

Until IS lost eastern Mosul, families could still pay their way out of the west by handing over 50,000 to 75,000 Iraqi dinars per person - about $60. Now their only option is to try and sneak out of the city under cover of darkness.

People there are literally on the verge of starving to death - Ahmed, Mosul resident

On Monday night, the Golden Division received 19 civilians - seven women, six men and six children - who had risked death at the hands of IS to make their escape.

They crossed Mosul’s Fifth Bridge, blown up by IS but the remains of which are still navigable on foot, though dangerous.

"The situation on the west side is very desperate, with no drinking water, fuel, or even food," said Ahmed, 25, whose sister remains stranded in her home across the river.

"People there are literally on the verge of starving to death."

Although mobile phones are forbidden by IS, and being found with even a SIM card now carries the death penalty, Ahmed said his sister had one and was able to occasionally make calls in secret.

"We try to speak to each other ever few days, just so we know they are still alive," he said.

"We always try to give them hope and tell them that the army is coming and will cross the river soon."