George de Dunbar, 11th Earl of March, had been forfeited his Scottish estates in 1434 after a long-running dispute with the Stewart crown. James I of Scotland gave Dunbar Castle to William Douglas, 2nd Earl of Angus, as Warden of the Marches. George went south to find allies among the English. The Percys of Northumberland, perpetually entangled with the Borders, took up his cause. Henry Percy, 2nd Earl, was nephew to the famous Hotspur killed at Shrewsbury in 1403, and he brought to Piperdean the family's standing grudge against the Douglases and against Scotland generally. Four thousand men marched north.

Angus had a roughly equal force and the home-ground advantage. He moved south with Adam Hepburn of Hailes, Alexander Elphinstone of that ilk, and Alexander Ramsay of Dalhousie, a coalition of east-coast lairds whose lands sat directly in the path of any English advance. They surprised the Percy column on the move. The fighting was sharp and one-sided. George Ridpath's 1776 Border History records the location as Pepperden on Brammish, the Breamish River that drains down from the Cheviot Hills, which puts the battle near Wooler in Northumberland, not in Scotland at all. The site is now generally placed near Wark on the Pressen Burn. Northumberland retreated to Alnwick Castle. Angus held Dunbar. The English lost a noticeable share of their Border knighthood: 40 named knights, by chronicle accounts, alongside the larger toll of footmen and men-at-arms whose names history rarely keeps.

Medieval battle accounts swelled and shrank with the chronicler's politics. The Scottish writers liked Piperdean. They put English losses at 1,500 and called it an overwhelming victory. The English versions were briefer and less specific. Gerald Brenan, writing a Percy family history in 1902, concurred that Scottish losses were trifling, which is one of those carefully chosen 1900s words that translates as the Scots got off lightly. Among the 200 Scots dead was Alexander Elphinstone of that ilk, whose family seat lay near Edinburgh. The fact that the records preserve his individual death and not the names of the four hundred-odd English knights and footmen below knightly rank tells you about whose deaths the chroniclers thought worth recording, then and since.

Piperdean was a holding action in a longer war. Henry Percy did not stay defeated. Within months he marched north again to relieve the siege of Roxburgh Castle, which James I of Scotland was personally directing. Roxburgh held; the Scots withdrew; the Borders settled back into their normal state of low-intensity raiding and counter-raiding. The Anglo-Scottish frontier would stay contested for another two hundred years, through the wars of the Tudor century and the Rough Wooing of the 1540s. Piperdean is remembered, if at all, as the moment when an English attempt to put George de Dunbar back in Dunbar Castle came to grief at the hands of an alert Scots warden, fifteen miles inside England, on a stream most people have never heard of.