Roger played a major part in the 1282-83 campaign and on 30 October 1282 succeeded Roger Mortimer, 1st Baron Mortimer as the English commander in mid-Wales. On 11 December he fought at the battle of Orewin Bridge, in which Llywelyn ap Gruffydd was killed - Lestrange wrote the letter informing Edward of his death. From 1283 he took part in the siege and capture of Castell y Bere. In 1284 he took part in Edward's castle-building campaign in north Wales In 1287 he took part in the suppression of Rhys ap Maredudd's revolt and the siege of Dryslwyn Castle, as well as the suppression of the 1294 Welsh uprising under Madog ap Llywelyn and the 1295 Gascogny and 1297 Flanders campaigns. On 21 October 1283 he was transferred to the role of justiciar of the "Forest south of the Trent", which he held until 12 February 1297.