Andrew Harclay, 1st Earl of Carlisle (c. 1270 – 3 March 1323), alternatively Andreas de Harcla, was an important English military leader in the borderlands with Scotland during the reign of Edward II.

His greatest achievement came in 1322, when he defeated the rebellious baron Thomas of Lancaster at the Battle of Boroughbridge on 16–17 March.

As one of the main military leaders on the border to Scotland, Harclay became frustrated with Edward II's inactivity, particularly the humiliating English defeat at the Battle of Old Byland on 14 October 1322, which made it clear that the war could not be won.

Harclay initiated negotiations with the Scots on his own accord, and on 3 January 1323, he signed a peace treaty with Robert the Bruce.

The first documented appearance of Andrew Harclay was at a Westmorland eyre in 1292, at which point it must be assumed that he was at least twenty-one years old, and therefore born in the early 1270s.

His meteoric rise over the previous years had made him some enemies in local society, who now took the opportunity to spread slanderous rumours about him at court.

[4] It was not until 1319 that he once more was appointed sheriff, and at the same time made keeper of Carlisle and Cockermouth castles, and Warden of the West Marches.

The battle was the culmination of an ongoing struggle between King Edward II and his most powerful earl, Thomas of Lancaster.

[8] His orders were to meet up with the royal army, but while stopping at the town of Ripon in Yorkshire, he received intelligence that Lancaster would arrive at nearby Boroughbridge the next day.

The rebels were greatly outnumbered; while Harclay commanded around 4000 men, Lancaster only had some 700 knights and men-at-arms, with followers, in his service.

[10] The Lanercost Chronicle describes how Harclay employed the Scottish schiltron – a compact formation of infantrymen with pikes or spears, highly effective against Lancaster's cavalry-heavy forces.

[12] According to The Brut, Lancaster tried to persuade Harclay to join his side, in return for great rewards in land.

[20] On 14 October 1322, the English army was routed by the Scots, under the command of Robert the Bruce, at the Battle of Old Byland in Yorkshire.

When he heard the news he fled to York leaving behind the Great Seal of England and a large amount of treasure.

[23] Harclay had received a summons to join the royal army, but had not been able to bring his troops south in time to come to Richmond's rescue.

[29] It is also possible that Edward held a grudge against Harclay for the latter's failure to come to the rescue at Byland, and that this was behind the king's later, severe reaction.

[31] Lucy, who acted with only a small force, was clearly trusted by Harclay, so the arrest must have been conducted as a surprise manoeuvre.

Edward II's inability to win the war against the Scots, combined with his refusal to give up his claim on the Scottish crown, proved untenable in the end.

[36] Furthermore, it was Harclay's military skills and well-organised forces that gave what little protection the northern borders had over the previous years.