There had been a long standing feud between Clan Johnstone and Clan Maxwell with the feud coming to a head on 7 December 1593 at the Battle of Dryfe Sands near Lockerbie. The Clan Maxwell army approached the Johnstone town of Lockerbie. Johnston kept his large force of men hidden; only sending a handful of men out on horseback to taunt and provoke the Maxwells. The Johnstones attacked, taking the Maxwells by surprise as they were attempting to ford the river Annan. It is said that up to 700 Maxwells were killed, but this may be an exaggeration. Lord Maxwell, who was one of the most powerful people in southern Scotland, was slain in cold blood by the Johnstones when he asked for mercy and offered to surrender. Sir Johnstone escaped punishment from the King for his actions, but he did not escape the unforgiving hand of the next Lord Maxwell, son of the chief who was killed at Dryfe Sands. In 1608, Lord Maxwell shot Sir Johnstone in the back during a meeting held “under trust,” which rendered him, Lord Maxwell, an outlaw. Lord Maxwell was later captured and executed by hanging.
A more detailed Clan history can be found on the Clan Johnston/e website. You can access it by clicking on the link in the upper left-hand corner of the page.