At some point in the 13th century the Bruces built a castle, probably a Keep, at Lochmaben, the remains of which now lie under a golf course. It is claimed that King Robert I of Scotland (Bruce) was born there, which is why the town adopted the motto "From us is born the liberator king" (in Latin) on its coat of arms. However this claim is relatively late, it cannot be ruled out, but his birthplace was more likely Turnberry Castle. Bruce certainly battled the English over this area during the Wars of Scottish Independence.

King Edward replaced the castle with a much sturdier structure at the south end of Castle Loch around 1300 and its remains still show the massive strength of its defences. Archibald Douglas, Lord of Galloway, with the assistance of the Earls of March and Douglas, after a siege of nine days, took Lochmaben Castle from the English and "razed it to the ground" (probably meaning it was burnt) on the 4th February 1384/5. The castle and barony became a possession of the Earls of March, but when the 10th Earl was forfeited and then reinstated, in 1409, it is noted that it was "with the exception of the castle of Lochmaben and the Lordship of Annandale."

The Battle of Lochmaben Fair was fought on 22 July 1484: a force of 500 light horsemen led by Alexander Stewart, Duke of Albany and James Douglas, 9th Earl of Douglas invaded Scotland, but were defeated.

On the 16 January 1508/9, at Edinburgh, Sir Robert Lauder of The Bass (d.1517/8), knight, was appointed "Captain and Keeper of the King's castle and fort of Lochmaben, with all pertinentes" and other privileges etc., for three years.

Lochmaben remained important and had a turbulent history until after 1600 by which time the castle had seen its last siege and was gradually abandoned.