A distinguished soldier, FitzRoger fought in wars in Wales in 1277, 1282 and 1283, the wars against Scotland in 1291 until 1309 and in Gascony in 1294. He was summoned to the English Parliament of 1295 as Lord FitzRoger. During the battle of Stirling Bridge in 1297, fitzRoger was captured. He was a joint Captain of the Scotch Marches from November 1297. FitzRoger fought with his son John at the battle of Falkirk in 1298 and the siege of Caerlaverock in 1300. FitzRoger signed the Barons' Letter of 1301. He conducted a foray with John de Segrave from Berwick in 1302, and fought at the battle of Methven in 1306. He died in 1310.