Battle of Oxcross

The Battle of the Oxcross was an battle in the War of the Five Kings, a massive civil war that erupted in Westeros after the death of King Robert Baratheon. It is depicted in the fourth episode of the third season of Game of Thrones.

Season 3
Having won three victories, and liberated the part of the Riverlands and Riverrun, Robb Stark invades the Westerlands.

Grey Wind silently eliminates a number of Lannister guards. To the cry of "the King in the North!" uttered by Greatjon Umber, the Northern army descends on the Lannister host under the command of Ser Stafford Lannister. "Garden of Bones"

Aftermath
The battle results in five dead Lannister men for each of House Stark's and a number of highborn prisoners. Roose Bolton advocates torturing the prisoners for information and eliminating the surviving men-at-arms but King Robb refuses to do so despite Bolton's reminder that they are having trouble keeping the army well fed. Some Northern soldiers loot the dead, and King Robb meets a woman helping the Silent Sisters tending to the wounded.

Meanwhile, in the capital, it is reported that Robb Stark attacked with sorcery and an army of wolves and that the Northmen feasted on the flesh of the slain.

In the books
In the A Song of Ice and Fire books the battle is not shown directly but rather told to Catelyn Stark. Roose Bolton doesn't participate as he's leading the joint Northern-Frey armies east of the Trident. Instead, Brynden Tully, Rickard Karstark, Galbart Glover, Greatjon Umber, Maege Mormont and Ser Stevron Frey take part. Karstark is the one to slay Stafford Lannister and then descends on the Western coast with Glover to raid. Ser Stevron Frey, Walder Frey's heir, perishes from wounds taken during the battle. Ser Lymond Vikary and Lord Antario Jast, Lannister bannermen, are also slain.

The Stark battle it is Rickard Karstark the one to kill Stafford Lannister, while the episode makes no mention. Also, Ser Stevron Frey, Walder Frey's heir perishes shortly after due to wounds taken in battle.