A man of apparently dashing bearing, Douglas was with the Franco-Scots army when it unsuccessfully besieged Carlisle Castle in 1385, the defending Governor being Lord Clifford.
According to Andrew of Wyntoun: A yhowng joly bachelere Prysyd gretly wes off were, For he wes evyr traveland Qwhille be se and qwhille be land To skathe his fays rycht besy Swa that thai dred him grettumly Douglas certainly had gained his spurs by 1387 when he married Egidia Stewart, Princess of Scotland, a daughter of King Robert II and Euphemia de Ross.
Within his first year of marriage the young Nithsdale led a punitive raid against Irish raiders who had been troubling the tenantry of his father's Fiefdom of Galloway.
Nithsdale's expeditionary force sailed back into Loch Ryan with enough time to join his father and the Earl of Fife and Menteith who had just led an expedition over the western marches into Northern England while a second army under James, 2nd Earl of Douglas, simultaneously led an expedition into England by the eastern marches, which culminated in the Battle of Otterburn.
Clifford, however, died on 18 August 1391,[1] but Nithsdale is said to have kept their "tryst", and whilst walking upon the bridge leading to the main gate at Danzig was "killed by the English".