This was also the year he went to war for the first time, summoned to fight in France, but then diverted to Wales to join Edward I in suppressing a Welsh rebellion.

In 1294 Philip IV of France had taken back Aquitaine from the English crown and now negotiated a treaty with the Scots to wage war on Edward on two fronts.

[8] Later on the same day the town was taken and the ruthless king, apparently provoked by the inhabitants previously baring their buttocks at him, ordered the city put to the sword "whatever the age or sex" and according to the Scotichronicon 7,500 were executed.

[9] Percy, under Warenne's command, was sent north to Dunbar where the castle was held by the Earls of Mar, Menteith and Ross, together with many lesser nobles.

In the following spring of 1298 King Edward returned from France and assembled a large army, including many Welsh longbow archers, to begin a new and determined assault on Scotland.

They caught up with Wallace at Falkirk on 22 July where Henry Percy was part of the fourth reserve division of experienced and highly mobile cavalry.

[10] Early in 1299 the King granted the estates of Ingram Balliol, who had been involved in the Scottish rebellions, to Henry Percy, including land in England and south west Scotland.

The rest of the year was spent skirmishing with Scottish guerilla groups, and the following summer campaigning with the king although little was achieved other than the capture of Caerlaverock Castle after a long siege, at which he was present with his elderly grandfather Earl Warenne.

The Caerlaverock Poem or Roll of Arms made at the siege by the heralds records the armorials of Warenne and Percy in a single verse, translated from Norman French into modern English thus:[11] "John the good Earl of Warenne Of the other squadron held the reins To regulate and govern, As he who well knew how to lead, Noble and honourable men.

A blue lion rampant on yellow Was his banner very conspicuous" Correspondence in late 1301 shows Percy at his estate at Leconfield in Yorkshire, where his wife probably lived, at a safe distance from Scottish raiding parties.

[12] Only Stirling Castle now remained to be subdued, and was battered by catapults during the spring of 1304, while King Edward's militant queen, Marguerite of France, watched from a specially built wooden shelter.

On 25 March 1306 Robert Bruce was crowned King of Scotland at Scone Abbey, upon which Edward confiscated his lands and gave them to Henry Percy.

After years of hard fighting he now had extensive land holdings in southern Scotland, but this was of less interest to Edward II who promptly recalled Gaveston and made him Earl of Cornwall, an office of great wealth.

In 1309, Henry was able to buy Alnwick Castle from Anthony Bek, the Prince Bishop of Durham, giving him a base near to the action in Scotland and a substantial annual income of about £475 from the associated lands.

Vesci of Kildare did receive the other family lands in Yorkshire and Lincolnshire and it is unclear whether he was defrauded by the greedy bishop over the sale of Alnwick.

On 27 June 1309 Gaveston, restored to the Earldom of Cornwall, returned to England and soon proved as obnoxious as before, calling Lancaster "Churl" and Warwick "Black Cur".

Robert Bruce continued to fight a guerilla war, refusing to give battle, so little was achieved, while relations between the king and his earls further deteriorated.

In May 1311 Gaveston ordered Percy to hold Perth for the summer with two hundred knights and no infantry, a dangerous task at a time when the king's army was withdrawing to England.

[16] The barons now forced the king to send Gaveston into exile in Flanders, but he was soon recalled and was in York with his heavily pregnant wife in January 1312, with his lands restored.

In April the king and Gaveston were chased out of Newcastle by the sudden arrival of an army under Lancaster, Percy and Clifford, fleeing to Scarborough.

In their haste they left behind Gaveston's wife and baby daughter and a great hoard of treasure, which it took Lancaster, Percy and Clifford four days to catalogue.

The king, seeking revenge for the death of his favourite, stopped short of civil war with the rebel earls but made an example of the less powerful Baron Percy by confiscating his lands on 28 July 1312, and having him imprisoned by the Sheriff of Yorkshire.