Arundel was a key member of the group of nobles called the
Lords Appellant, who had emerged as opponents of Richard II and the royal favourite
Robert de Vere, Duke of Ireland. Mortimer was closely associated with them and is known to have visited Arundel's house regularly during 1387, the critical year in the Appellants' rise to power.
The Battle of Radcot Bridge In December 1387, at
Radcot Bridge, the Appellants clashed with the royal army, headed by Robert de Vere and Sir Thomas Molineux, Constable of
Chester Castle; de Vere was defeated and forced to flee the country. Mortimer himself killed Molineux, who was one of the few casualties of the fight. According to
Thomas Walsingham, Molineux, who had attempted to flee, pleaded for his life, but Mortimer pulled off Molineux's
helmet and stabbed him in the head with a
dagger. During the brief rule of the Appellants, Mortimer was in high favour. He was appointed Justiciar of Ireland, but Richard, despite his temporary loss of power, somehow managed to countermand the appointment (no doubt he feared surrendering control of Ireland entirely to his enemies) and it never took effect. Despite the King's mistrust of them, Thomas and his nephew Roger, with troops, accompanied him on his Irish expedition in 1394; and when Roger was reappointed Lord Lieutenant in 1396, Thomas went to Ireland with him. ==Downfall==