Question: What type of surety was the Earl of Pembroke who participated in the battle at Lincoln castle in 1217?
Context: During the First English Civil War Lincoln was besieged between 3 May and 6 May 1644 by Parliamentarian forces of the Eastern Association of counties under the command of the Earl of Manchester.  On the first day, the Parliamentarians took the lower town.  The Royalist defenders retreated into the stronger fortifications of the upper town, which encompassed and incorporated Lincoln Castle and Lincoln Cathedral.  The siege ended four days later when the Parliamentarian soldiers stormed the castle, taking prisoner the Royalist governor, Sir Francis Fane, and what remained of his garrison. Richard Marshal, 3rd Earl of Pembroke (1191 – 16 April 1234) was the son of William Marshal, 1st Earl of Pembroke and brother of William Marshal, 2nd Earl of Pembroke, whom he succeeded to the Earldom of Pembroke and Lord Marshal of England upon his brother's death on 6 April 1231. Lincoln Castle is a major castle constructed in Lincoln, England, during the late 11th century by William the Conqueror on the site of a pre-existing Roman fortress.  The castle is unusual in that it has two mottes.  It is only one of two such castles in the country, the other being at Lewes in Sussex.  Lincoln Castle remained in use as a prison and law court into modern times, and is one of the better preserved castles in England; the Crown Courts continue to this day.  It is open to the public as a museum.  Lincoln Castle remains one of the most impressive Norman castles in the United Kingdom.  It is still possible to walk around the immense Norman walls which provide a magnificent view of the castle complex, together with panoramic views of the cathedral, the city, and the surrounding countryside. The Second Battle of Lincoln occurred at Lincoln Castle on Saturday 20 May 1217, during the First Barons' War, between the forces of the future Louis VIII of France and those of King Henry III of England.  Louis's forces were attacked by a relief force under the command of William Marshal, 1st Earl of Pembroke.  Thomas, the Comte du Perche, commanding the French troops, was killed and Louis was expelled from his base in the southeast of England.  The looting that took place afterwards is known as the "Lincoln Fair".  The citizens of Lincoln were loyal to Louis so Henry's forces sacked the city. Baron Herbert of Lea, of Lea in the County of Wiltshire, is a title in the Peerage of the United Kingdom, since 1862 a subsidiary title of the earldom of Pembroke.  It was created in 1861 for the politician Sidney Herbert.  He was the fourth son of George Herbert, 11th Earl of Pembroke.  Lord Herbert of Lea died only a few months after his elevation to the peerage and was succeeded by his son, George, the second Baron, who already the following year succeeded his cousin in the earldom of Pembroke.  The titles remain united, the current holder being William Alexander Sidney Herbert, 18th Earl of Pembroke, 15th Earl of Montgomery.  The heir apparent is his son, Reginald Henry Michael Herbert, Lord Herbert, born on 21 October 2012. PS "Lincoln Castle" was a coal-fired side-wheel paddle steamer, which ferried passengers across the Humber from the Second World War until 1978.  She was the last coal-fired paddle steamer still in regular services in the UK.  Later, she served as a pub at Hessle, and then as a restaurant under permanent dock in Alexandra Dock Grimsby.  In September 2010, the "Hull Daily Mail" reported that she was in an advanced state of demolition, despite the efforts of local people to buy the historic vessel and restore her.  On 31 March 2011, The Lincoln Castle Preservation Society were reported to have purchased the broken up parts of the ship for restoration. William Marshal, 2nd Earl of Pembroke (French:"Guillaume") (1190 – 6 April 1231) was a medieval English nobleman and was one of Magna Carta sureties.  He fought during the First Barons' War and was present at the Battle of Lincoln (1217). The Old Bishop's Palace is an historic visitor attraction in the city of Lincoln, Lincolnshire.  When it was first built, in the late 12th century, it was at the centre of the vast Diocese of Lincoln, which stretched from the Humber to the Thames.  The Palace was one of the most impressive buildings of medieval England, reflecting the power and wealth of Lincoln’s bishops.  It is situated on a spectacular hillside site, just below Lincoln cathedral, providing extensive views over the city.  The site lies immediately to the south of the Roman wall which had become the medieval defensive wall of the "Bail", which enclosed both Lincoln Castle and Lincoln Cathedral.  The palace was damaged during the Civil War and subsequently largely abandoned.  During the period that followed the Bishop’s main residence was Buckden Palace in Huntingdonshire.  In 1841, following the reduction in size of the Diocese of Lincoln, the Bishop moved to Riseholme, to the north of Lincoln.  This proved inconvenient and Riseholme was sold.  In 1886 an older building on the western side of the Palace enclosure was substantially rebuilt and enlarged in a Tudor revival style by the architect Ewan Christian.  A further change occurred in 1888 when the architects Bodley and Garner rebuilt and converted the southern portion of the medieval Great Hall into a chapel for the Bishop. William de Lanvallei III (died 1217) was an English landowner, governor of Colchester Castle, and a Magna Carta surety.  He was lord of Walkern.  William III accompanied King John of England on his expedition to Poitou in 1214 and was present at the truce.  William III was related to several of the Magna Carta barons. Margaret de Quincy, 2nd Countess of Lincoln "suo jure" (c. 1206 – March 1266) was a wealthy English noblewoman and heiress having inherited in her own right the Earldom of Lincoln and honours of Bolingbroke from her mother Hawise of Chester, received a dower from the estates of her first husband, and acquired a dower third from the extensive earldom of Pembroke following the death of her second husband, Walter Marshal, 5th Earl of Pembroke.  Her first husband was John de Lacy, 2nd Earl of Lincoln, by whom she had two children.  He was created 2nd Earl of Lincoln by right of his marriage to Margaret.  Margaret has been described as "one of the two towering female figures of the mid-13th century".
Answer: Magna Carta