[4] At Candlemas 1400 George I, Earl of March and Henry 'Hotspur' Percy had entered Scotland and laid waste as far as Papple in East Lothian.

The Master of Douglas, who held the office of Lord Warden of the Marches, surprised them by night at their camp near East Linton and defeated the English Force.

[5] Later that summer Douglas was second in command to David Stewart, Duke of Rothesay, the lieutenant of the Kingdom, during the siege of Edinburgh Castle by Henry IV.

Henry was unsuccessful in his endeavours and with Owain Glyndŵr's rebellion gathering apace in Wales, he became the last English monarch to ever invade Scotland in person.

However, on 16 March, both men were acquitted when Parliament passed an act stating that the Prince had: "departed this life through Divine Providence, and not otherwise", clearing both of High Treason, and any other crime, and strictly forbidding any of the King's subjects to make the slightest imputation on their fame.

[8] On 22 June the same year, a small Scots force was beaten by George Dunbar, the Earl of March's son, at the Battle of Nesbit Moor.

The Scots did, however, have keen sentries and the army was able to retreat to the higher ground of Homildon Hill and organise into traditional schiltron formations.

Douglas had not learnt the lessons that had defeated his great uncle at the Battle of Halidon Hill seventy years previously, and the schiltrons presented a large target for the English Longbowmen, and the formations started to break.

By 1403, Hotspur was in open rebellion against his King, joining with his kinsman Thomas Percy, Earl of Worcester, whilst Owain Glyndŵr was undertaking a campaign against English rule in Wales.

In the chivalric spirit of the time, Douglas marched with his former enemy Hotspur and his forces to the meet with King Henry IV at the Battle of Shrewsbury.

King Henry wrote to Regent Albany complaining of this "un-knightly" behaviour and warned that unless Douglas returned the hostages would be dealt with at his pleasure.

Douglas went to Flanders and France in 1412, whereupon arriving in Paris he entered into negotiations with John the Fearless, Duke of Burgundy, whereby they agreed to a mutual defence and offence pact in their respective countries.

However, it appears that Albany was not prepared to pay for this, so Douglas recovered his costs from customs fees on all trade goods entering the country.

Douglas's son, the Earl of Wigtoun, had been fighting in France with his son-in-law Buchan, where they defeated the English at the Battle of Baugé in 1421.

In 1423 Wigtoun and Buchan returned to Scotland to raise more troops for the war effort, and with a personal request to Douglas from Charles VII of France to lend his aid.

Of their children: The 4th Earl of Douglas is represented in William Shakespeare's Henry IV, Part 1 from the defeat at Homildon to his release following the Battle of Shrewsbury.