Roose Botlton's POV
His force had marched through the night from the Twins to catch the Tywin's force by surprise and cause some damage. He knew his troops would be tired but he was only going to hold Tywin's attention long enough for Robb Stark to lift the siege on Riverrun. His outriders bring news of Lannister scouts. He knows they must be preparing and know they are coming; surprise wouldn't work now he would need a new plan. As they continued marching he saw in the distance a hill just on the other side of the he decided to march his troops to that hill leaving 2,000 troops behind the hill and taking the rest to the top, he would send his cavalry down first to attack the vanguard and then they would pull always leading the vanguard behind the hill as if they were retreating, while his main force marched half way down the hill drawing in the in the centre force. Well that was theory.
Tywin's POV
His force were just moving to into position in the distance he could hear the drums and just coming over the hill he could see hundreds of banners. His reports form the scouts must be correct it was the whole Stark Host of 20,000 men who had come, bearing down of his army led by the green boy Robb Stark. He had put most of the undisciplined men, sellswords, freeriders and raw recruits although entirely mounted in the vanguard on the left commanded by Ser Gregor Clegane . He hoped that the inexperience of the commander would mean he would over commit there meaning Ser Gregor Cleganes forces will collapse there and the Northmen would plunge into the gap and eager to press the advantage but the Kevans forces of 300 heavy cavalry and the main infantry of 7000 men would wheel to the left and smash Robb's army on the flank, crushing the North in one single deceive victory. That was the plan, and he Lord Tywin Lannister always made sure his plans worked.
Roose's POV
At the top of the hill Roose saw a swathe of soldiers far more than his own host and fresh after a night's sleep not like his but it was time to draw Tywin in. Lord Tywin was en effective commander but Roose was sneaky and probably bot who Tywin thought was commanding the host he would use it to his advantage.
"Lord Hornwood get Harrion Karstark you 2 will command the cavalry you will launch down at their vanguard, we will fire volleys of arrows ahead of you to cause disruption. Do not fully engage attack all your forces make it look like your troops are out of control and they panic and retreat in a disorderly fashion behind the hill we will have a surprise waiting for all the troop that follow them."
He watched the his only cavalry lead a suicide charge, they were galloping fast, screaming waving swords around, at least half of them were freeriders and they normally did this but it was all part of the plan. The 300 smashed into the vanguard and for a moment it looked like their vanguard had buckled then Roose realised, where his cavalry were pretending to be undisciplined, Tywins van actually were hoping that he would over commit and get flanked but luckily his plan muted Tywins.
Tywin's POV
He smirked smugly as Stark's measly cavalry charged at his vanguard, Tywin knowing it would buckle under a charge and flurries of arrows that had been sent down before but then something happened as the starks cavalry smashed through the front line slashing and stabbing at anything in front of them, a few at the back panic and turned around followed by more and more eventually all that had survived the initial blow bolted slowly disorganised, knocking into each other. Then he realised his mistake, as they fled his undisciplined troops followed led by the idiot and savage Clegane.
He turned to his second in command of the reserve "Lorch order the sound of retreat, make the Van to pull back they are falling into a trap." A trumpet rang out but the most of the van were all to pumped up in the heat of battle thinking they had the upper hand and continued to chase the North's men around the hill as the Stark's centre force of infantry, drawing his brother's force of Cavalry out to meet them. They charged at the front line as arrows rained down on the cavalry with the infantry force bringing up the rear as the cavalry charged into the lines of pike and spearman slaughtering the first few lines but eventually breaking through.
Roose's POV
On the far side of the hill outside the view of Tywin Lannister, the Clegane vanguard was getting slaughtered. He had lined 2000 troops behind the hill near the river, 1000 near the river and 1000 at the base of the hill, as Lord Halys led the undisciplined troops into a the slaughter. Pikeman smashed the Lannister cavalry on either side.
Harrion karstark fell of his horse but maged to slash the Lannister bearing down on him in the stomach he turned around to face what could have been a giant: The Mountain. He quickly ducked a strike from Clegange long sword and was about to try and slash back but a pikeman charged up from behind Clegane stabbing his horse making him fall off and hit the ground hard, that was when Harrion sliced the mountains sword arm of through gap in his shoulder arm he then smashed down at his head ,crushing it underneath blow after blow after blow. "The mountain is dead" he cheered victoriously, he looked around, the last of the Lannister vanguard were running away behind chased down and killed then saw a man carrying a body Lord Halys laid dead in his arms
Roose turned back to the main battle his main was getting hammered by the heavy cavalry but they were holding their ground, he ordered the force to fall back to the top of hill to regroup and then signalled the force behind the hill to reform up and charge up the hill taking the Lannister cavalry by surprise as they pressed the attack thinking they had the advantage.
Tywin's POV
How was this happening, his Vanguard had disappeared from view probably destroyed, his brother Kevan had pushed the advantage of his heavy cavalry and large infantry host but the rains of arrows from the top of the hill had severely lessened the force then, when it looked like the cavalry had the advantage another force came from behind charging instead of retreating and smashed into Kevans remaining disarrayed forces as the retreating force turned back and joined in the massacre.
How was this happening he had never been defeated was his old age making him make mistakes, he still had at least another 14-15 thousand men left enough to defeat what was left of this force obviously not the whole Stark army now but enough to hold him for a little while. But what angered at the back of his mind was where were the rest of them where had they crossed and then a rider brought the bad news. "My lord Tywin the Siege on Riverrun has been lifted, we were ambushed. What was left of the force under Ser Forley Prester has retreated east from their camp planning to cross Red Fork and head to the golden tooth with his 3000 men"
"My son?" he asked afraid of the answer.
"I don't know Lord he led a sortie when Lord Piper launched a raid on our camps hoping to catch him in the whispering woods but then we were attacked and we don't know what happened, I'm sorry lord but there's more bad news, The Storm's lord force is marching up King's Road from King's landing they will be here in day or less."
Damm this had all been a distraction that had tricked him.
"Sound the retreat fall back in a fashion. I will not get caught between 2 maybe 3 forces we will move through the Riverlands, Ser Amory you will lead the rear guarding burning and pillaging behind us slowing them down if you can. We will fall back to the Golden Tooth and fend the Westerlands at all cost."
Roose's POV
He thought he would only hold them not force a retreat maybe it had something to do with the Stormlord's army or Robbs attack on Riverrun but anyway eh would claim credit, they had lost good soldiers including Lord Halys Hornwood and Medger Cerwyn and had killed worthy adversaries, Ser Gregor Celegane, and Ser Adam Madbrand aas he had tried to retreat they had also captured Kevan Lannsister the old lion's brother.
"Everyone kill any other Lannister left alive no time for prisoners, we will press forward to Harrenhal where we will rest and hold the line, while the Stormlords catch up."