He was summoned a number of times to Parliament from 1291 until 1322 as Baron Braose. He was the second Baron Braose, as well as Lord of Gower and Lord of Bramber. After his father's death, Braose continued to serve Edward. He contributed both money and personal military service in Edward's wars in Wales, Scotland, and France. He saw service in Gascony in 1294. In 1297 he took part in a military campaign in Flanders. As a reward for his service in Flanders, he received the wardship of John de Mowbray, who Braose eventually married to his daughter Aline. From 1298 to 1306 he was involved in the Scottish wars, and was at the Battle of Falkirk on 22 July 1298. Besides the military service, he served the king in 1301 by signing a letter from the leading barons of England to Pope Boniface VIII in which the barons decried papal interference in the royal rights of England. Braose captured the Welsh rebel William Cragh in 1290, whose miraculous resurrection after being hanged was attributed to Thomas de Cantilupe. This led in 1307 to Braose giving testimony to papal commissioners inquiring into the events surrounding Cragh's hanging and whether or not it would support the canonisation of Cantilupe. It was most likely Braose who commissioned a condensed copy of Domesday Book, now Public Record Office manuscript E164/1. This copy has a marginal notation of "Br" next to the estates owned by Braose's ancestor, the first William de Braose. Braose was embroiled in a dispute over his lordship of Gower in 1299 when the Bishop of Llandaff, John de Monmouth, brought a case against Braose to the king. Although the case was adjudicated in 1302, the resulting decision was overturned. In 1304 Braose secured King Edward's confirmation of earlier grants and charters granting Braose special rights and liberties in Gower. He managed this because he was serving the king in Scotland at the time, and thus had easy access to the king. In 1305, however, Braose miscalculated and insulted a royal judge, using "gross and contumelious words" to describe the royal official. This episode caused the case of Gower to be reopened in 1306, and Braose was only able to settle the issue again by the grant of rights to his men in Swansea and Gower. In 1320 King Edward II of England confiscated the lordship of Gower on the grounds that Braose had given it to his son-in-law Mowbray without royal permission.