Meritt was a male mouse and a member of the Guard. During the Battle of Lockhaven in the Fall of 1152, Meritt was ordered by Rand to lower the portcullis to secure Lockhaven. However, the portcullis couldn't be lowered because of the rain rusting the lowering mechanism.
After the Axe army had entered Lockhaven, Meritt just managed to lower the portcullis and stop the rest of the army's intrusion; before he was subsequently shot and killed by an archer. Two axe-mice were crushed and killed by the portcullis in the process.