IRAQ -- On Christmas Eve, Soldiers in Staff Sgt. Johnathan Walker's section shiver as freezing rain falls upon their position."Fire!" yells Walker as he makes a cutting motion through the rain with his hand. A round leaves the tube of the M777 artillery piece with its trademark boom and smoke, and the artillerymen begin to move again. The sounds of their boots impacting the mud and gravel echo through the gun pit.It may be the holiday season, but the mission for the Soldiers of Battery C, 1st Battalion, 320th Field Artillery Regiment, Task Force Strike, continues. The Iraqi Security Forces are battling ISIL in Mosul, and the artillerymen are supporting them with indirect fires."We provide overmatch capability to the maneuver commander," explained Sgt. 1st Class Scott Young, the platoon sergeant of 2nd Platoon, Battery C, during his rounds of the gun line. "When air support isn't available, either due to weather or not having the assets in the area, we can bring effects onto targets. As long as there is an observer out there, we can shoot.""Task Force Top Guns" has provided fire support for the Iraqi Security Forces ever since arriving in early May. The battery has fired more than 4,000 rounds in support of their maneuvers.They're also credited with conducting the first conventional air assault mission during Operation Inherent Resolve, during which they rapidly moved artillery pieces by air to establish a new firing position. At the completion of the fires, the guns were moved back to their starting location."We've denied territory so the enemy can't maneuver, obscured friendly movements, and we have precision capability, which is critical in this fight," Young said, pointing in the direction of Mosul to emphasize his point."If there is a target in a built-up area, we can hit it while minimizing damage to the surrounding area. We pride ourselves on our accuracy."RAIN OR SHINEThe rain picks up and a slight fog takes shape in the distance as Walker's crew awaits their next command. The weather has changed in Iraq, and the Soldiers have switched from their summer lightweight combat shirts to multiple layers in an attempt to stave off the wind-chill."Fire mission at my command," comes the transmission over the radio, and the artillerymen spring into action, beginning the crew drill to load the artillery piece, just as they have done for the past eight months. The Soldiers move quickly through their tasks, and Walker gives the signal once more. Another boom reverberates in the pit."It feels good to know that we're being called on to support the fight and we're having an effect," Walker said in between missions. During each crew drill, he encourages his men to keep up the effort. "That's the reason why we're out here. We do everything with a sense of urgency and there's no room for mistakes."Battery C has received multiple calls for fires as the Iraqi Security Forces have moved deeper and deeper into Mosul, the second largest city in Iraq and the site of a major operation with the goal of liberating the city. ISIL has been dug into the city for two years."There's a lot more variables in weather like this," said Walker. "People move a little slower, the rounds are slippery, and morale may drop. It's the job of crew chiefs on the line to keep on pushing the sections to complete the mission. Rain or shine, when we get the call, we have to react."The radio sounds soon after, and the artillerymen are once again called to action.