In the wake of the their defeat at the Battle of Ludford Bridge in October 1459, several of the Yorkist commanders, including the Earl of Warwick, Earl of Salisbury, and the Earl of March, fled across the Channel to Calais.
Other Yorkist leaders, including the Duke of York, retreated to Ireland. Despite Lancastrian efforts to assert their control over Calais and Ireland, they were unable to do so due to the strong Yorkist presence. As a result, preparations were made to cross the Channel and take Calais by force. Construction soon began on a transport fleet at Sandwich.
Learning that the transports were completed, Warwick launched a raid on Sandwich and captured the ships. Taking them back to Calais, he and the other Yorkist commanders began planning an attack on England. When the Lancastrians renewed their efforts to build a fleet at Sandwich, Warwick attacked and occupied the town in May 1460.
Leaving a small Yorkist force in Sandwich, he returned to Calais to prepare his army. On June 26, he returned with 2,000 men. Marching on London, the Yorkist ranks quickly swelled to 20,000-30,000 men.
Alerted to Warwick's arrival in England, King Henry VI elected to move his 10,000-15,000-man army from Coventry to Northampton. Commanded by the Duke of Buckingham, the king's army occupied a defensive position along the River Nene.
Placing the river at their back, they dug a water-filled ditch across their front and topped it with pointed stakes. Though the bulk of Henry's army consisted of men-at-arms, he did possess some field artillery. Informed that Henry's army had shifted, Warwick moved north from London towards Northampton.
While his army was on the march, Warwick dispatched a messenger asking to meet with the king. Arriving at Northampton, this messenger was denied access to Henry by Buckingham and told that "The Earl of Warwick shall not come to the King's presence and if he comes he shall die." Not to be denied, Warwick sent two more messengers before reaching the battlefield.
As his army arrived opposite the Lancastrian position, Warwick sent a final message stating "At 2 o'clock I will speak with the King or I will die." As 2:00 approached, Warwick's men formed into columns and prepared to attack.
Moving forward, the Yorkist troops were forced to endure a shower of arrows from the Lancastrians as well as were made to cope with driving rain. Though the rain slowed the advance, it prevented the Lancastrians from effectively using their artillery. Focusing his attack on the Lancastrian right, commanded by Lord Grey of Ruthin, Warwick was stunned to see the enemy laying down their weapons. Deciding his fortunes would be best served by the Yorkists, Lord Grey and his command effectively defected in the middle of the battle.
With no opposition on his front, Warwick's men swarmed into the Lancastrian camp and turned to roll up Buckingham's line. Due to the constricted nature of his fortified position, Buckingham was unable to maneuver troops to block the Yorkist advance. Pressing their attack, the Yorkists routed the Lancastrians after about 30 minutes of fighting. Realizing that Henry was in danger of capture, Buckingham, as well as Lord Egremont and Lord Beaumont, fought to the death in an attempt to allow him to escape. Their efforts proved fruitless as Yorkist troops quickly seized the king from his tent.
Yorkist losses at the Battle of Northampton were minimal, while the Lancastrians suffered around 300 killed and wounded. The victory once again placed Henry VI under the control of the Yorkists. Lancastrian fortunes remained on the wane until their stunning victory at the Battle of Wakefield that December.