 the main route to the Norman capital, Rouen; armies invaded from Flanders and Blois, attempting a pincer movement, while rebels from Brittany invaded from the west.
In July 1173, Henry secretly traveled back to England to order an offensive on the rebels, meeting his Barons at Northampton, giving them instructions and then returning. Chief Justicar, Richard de Lucy captures the town but not the castle of Leicester.
In September, Earl Robert of Leicester lands with an army of Flemish mercenaries and meets with Earl Hugh Bigod at Framlingham, intending to relieve Leicester. They capture the royal castle at Haughley.
On 17 Oct 1173, Royal forces under the command of Richard de Lucy, the Chief Justiciar surprise the rebels at Fornham as well as Humphrey de Bohun Lord High Constable, Reginald de Dunstanville, the Earl of Cornwall, William of Gloucester, the Earl of Gloucester, and William d’Aubigny, the Earl of Arundel, the Earl of Norfolk’s son, Roger Bigod intercept the rebels fording the River Lark about 4 miles (6.4 km) north of Bury St Edmunds.
The rebel forces numbering around 3000 mercenaries were caught fording the River Lark about 4 miles (6.4 km) north of Bury St Edmunds. With his forces split, Leicester’s cavalry was captured and his mercenaries were driven into nearby swamps where the local peasants killed most of them. Leicester was captured, as was his wife, Petronilla de Grandmesnil, who had put on armour herself. She is said to have fled from the battle, only to be found in a ditch wanting to drown herself, Leicester remained in captivity until January 1177 when some of his lands were returned to him.
David, Earl of Huntingdon, brother of Scottish King William goes to the relief of Leicester. Simon de Senlis III, Earl of Northampton, is told by King Henry he can have Huntingdon – if he can capture it so promtly lays siege to it. To draw the royal army away from Huntingdon, on May 1174, an army led by Ansketill Malory, Constable of Leicester attacks Northampton. Although details are scant, it appears a battle took place under the walls of the town (possibly outside the north gate). The Burghers of the town are beaten with 200 killed and 200 taken prisoner. The victors then assault Nottingham.
Then on 8 July 1174, Henry arrives in England, first travelling to Becket’s tomb in Canterbury, where he announced that the rebellion was a divine punishment on him, and took appropriate penance. On 13 July, King William was defeated and captured by local forces in a short battle at Alnwick, crushing the rebel cause in the north. He is taken to Northampton, his feet tied under a horse, where he is brought before King Henry. Eventually King William is transferred to Falaise where he is forced to sign a treaty renouncing Scottish claims on Northumberland.
Henry then marches to Huntingdon which surrenders. The remaining English rebel strongholds quickly collapse and Henry accepts the rebels surrender at Northampton.