Creative Writing: Blood Brothers

The sudden silent caught Erick and the other Arendelle's officers by surprise. They turned and discovered that all the artillerymen were leaving their post and went down the stairs. Nelberg was immobile watching the deployment of the enemy army in the valley and didn't even turned.
"Sir, the artillerymen have deserted the cannons." Reinhard said getting close to the colonel.
"Lieutenant I'm old, but not deaf yet." Nelberg replied without stopping from watching the valley. His attention was centered in one of the twenty-four-pounders which was the only cannon not deployed. Its crew was in that moment starting to unhitch the great horses which had dragged it.
"They don't want to wait for the Southern Isles' reply." Knut said looking at one
An artilleryman who had been waiting in the stairs repeated the order and waved his arms towards the other bastion. Everybody could heard sound of pikes at work. In the wall of the nearby bastion they could see great pieces of masonry, which had been disguised as solid stone, falling to the ditch leaving four great square windows in the wall of the bastion.
"Weren't they supposed to be solid bastions?" Knut asked.
"It seems that there is a room inside them." Erick went up to the battlements and peered down. Four similar square windows had been carved in the faces of the bastion where he was."What are they doing?" He asked in loud voice.
"Waiting for that sixteen-pounder to shoot the first cannonball. We are going to left them that honor." Nelberg replied with a sardonic smile on his face.
As if the Southern Isles' crew had heard his words, the sixteen-pounder shot. In a strange silence they could see the cannonball crossing the sky and hitting the ravelin in the middle of the two bastions.

"Taking into account that it's the first shoot, it is very good." Nelberg said before shouting and order.
Erick could see the great cannonballs flying over the valley passing over the enemy cannons and falling on the groups of horses and oxes which had dragged them. Some of the iron balls fell among the animals killing and wounding several of them.
The sound of the cannonballs hitting the ground and the whinnies of the wounded animals quickly spooked the entire herd which started to run. The artillerymen who took care of them desperately tried to control them since they were the only possibility to move the cannons towards a safe place, but the thunder of the cannons and the chaos around them provoked by the fleeing soldiers made it impossible.
All the southern isles' units near the fortress had began to retreat, the correct word would have been run, trying to get away from the deadly cannons. But the valley was full of infantry companies and cavalry squadrons which had deployed to protect the cannons from a sally and now they were just easy targets for Nelberg's gunners who, once the draught animals had fleed, mercilessly loaded and fired once and again against the units in the valley.
After several rounds, one of the cannonballs hit a group of hussars which was near one of the cannons. The great iron ball bounced several times on the hard ground leaving a bloody gap among the ranks of the