King Robert won his first small success at Glen Trool, where he ambushed an English force led by Aymer de Valence, attacking from above with boulders and archers and driving them off with heavy losses. He then passed through the moors by Dalmellington to Muirkirk, appearing in the north of Ayrshire in early May, where his army was strengthened by fresh recruits. Here he soon encountered Aymer de Valence, commanding the main English force in the area. In preparing to meet him he took up a position on 10 May on a plain south of Loudoun Hill, some 500 yards wide and bounded on either side by deep morasses.