As his father had predeceased his own father, in 1286, Robert inherited the estates of his grandfather, Roger I de Clifford. Following the death of his mother, Isabella de Vipont, in 1291, he inherited a one-half moiety of the extensive Vipont feudal barony of Appleby in Westmorland, including Appleby Castle and Brougham Castle. During the outbreak of the Wars of Scottish Independence, in 1296, Brougham Castle became an important military base for Robert, and in 1300, King Edward I of England visited there. In 1308, Robert was granted the remaining moiety of the barony of Appleby, by his childless aunt Idonea de Vipont, and thus became one of the most powerful barons in England.
Career
During the reigns of the English Kings, Edward I and Edward II, Clifford was a prominent soldier. In 1296, he was sent with Henry de Percy, 1st Baron Percy to quell the Scots who asked for terms of surrender at Irvine. He was then appointed Governor of Carlisle. During the reign of King Edward I, he was styled Warden of the Marches, and during the reign of King Edward II, as Lord Warden of the Marches, being the first holder of this office. In 1298, he fought for King Edward I at the Battle of Falkirk, in which William Wallace was defeated, for which he was rewarded with Governorship of Nottingham Castle. In 1299, he was created Baron de Clifford by writ and summoned to Parliament. He won great renown at the Siege of Caerlaverock Castle, in 1300, during which his armorials were recorded by the heralds on the famous Caerlaverock Roll or Poem, which read : "Strength from wisdom drawing, Robert Lord de Clifford's mind is bent on his enemies' subjection. Through his mother his descent comes from that renowned Earl Marshal at Constantinople, said to have battled with a unicorn and struck the monster dead. All the merits of his grandsire, Roger, still in Robert spring. Of no praise is he unworthy; wiser none was with the King. Honoured was his banner, checky gold and blue, a scarlet fess. Were I maiden, heart and body I would yield to such noblesse!" Clifford was one of many who sealed the 1301 Barons' Letter to the Pope, in the Latin text of which he is described as Robertus de Clifford, Castellanus de Appelby. After the death of King Edward I, in 1307, he was appointed counsellor to his son, King Edward II, together with Henry de Lacy, 3rd Earl of Lincoln, the Earl of Warwick, and the Earl of Pembroke. In the same year of 1307, the new King appointed him Marshal of England, and in this capacity he probably organised Edward II's coronation on 25 February 1308. On 12 March 1308, he was relieved of the marshalcy, the custodianship of Nottingham Castle, and of his Forest justiceship, but on 20 August 1308, he was appointed captain and chief guardian of Scotland. In 1310, King Edward II granted him Skipton Castle, and he was created Lord of Skipton, being given the feudal barony of Skipton in Yorkshire, held until that date by Earl Henry de Lacy. Henry had married Margaret Longespée, Clifford's cousin and heiress of the feudal barony of Clifford, which had descended in the female line from Clifford's great-great-uncle, Walter II de Clifford, Margaret's maternal grandfather. Skipton Castle would later become the principal seat of the Clifford family until 1676. In 1312, together with Thomas Crouchback, 2nd Earl of Lancaster, he took part in the movement against Piers Gaveston, King Edward II's favourite, whom he besieged at Scarborough Castle.
